UNITED STATES SECURITIES AND EXCHANGE COMMISSION
                             Washington, D. C. 20549


                                  FORM 10-QSB/A


                                 Amendment No. 1


[X]  QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE
     ACT OF 1934

                  For the quarterly period ended March 31, 2005



[_]  TRANSITION  REPORT  PURSUANT  TO  SECTION  13 OR  15(d)  OF THE  SECURITIES
     EXCHANGE ACT OF 1934

          For the transition period from _____________ to _____________


                         Commission file number 1-31398


                        NATURAL GAS SERVICES GROUP, INC.
        (Exact name of small business issuer as specified in its charter)


            Colorado                                              75-2811855
(State or other jurisdiction of                               (I.R.S. Employer
 incorporation or organization)                              Identification No.)


                           2911 South County Road 1260
                              Midland, Texas 79706
                    (Address of principal executive offices)


                                 (432) 563-3974
                (Issuer's telephone number, including area code)


                                       N/A
              ----------------------------------------------------
              (Former name, former address and former fiscal year,
                          if changed since last report)


         Check whether the issuer (1) filed all reports  required to be filed by
Section 13 or 15(d) of the  Exchange  Act during the past 12 months (or for such
shorter period that the  registrant was required to file such reports),  and (2)
has been subject to such filing requirements for the past 90 days. Yes X  No
                                                                      ---   ---


                      APPLICABLE ONLY TO CORPORATE ISSUERS

         State the number of shares  outstanding of each of the issuer's classes
of common equity, as of the latest practicable date.

                  Class                              Outstanding at May 16, 2005

         Common Stock, $.01 par value                         6,782,764


         Transitional Small Business Disclosure Format (check one): Yes    No X
                                                                       ---   ---
                                                                       



                                EXPLANATORY NOTE

         We are filing  this  Amendment  No. 1 to our  Quarterly  Report on Form
10-QSB in response to comments  received by us from the Staff of the  Securities
and Exchange Commission.  Unless otherwise stated, all information  contained in
this amendment is as of May 16, 2005, the filing date of our original  Quarterly
Report on Form 10-QSB for the fiscal  quarter  ended March 31, 2005. As a result
of this  amendment,  Natural Gas Services  Group,  Inc. is filing as exhibits to
this Amendment No. 1 on Form 10-QSB/A the certifications pursuant to Section 302
and 906 of the Sarbanes-Oxley Act of 2002. This Amendment No. 1 on Form 10-QSB/A
does not change our previously reported financial statements and other financial
disclosures.

         Items included in the original Form 10-QSB that are not included herein
are not  amended  and  remain in effect as of the date of the  original  filing.
Additionally,  this Form  10-QSB/A  does not  purport  to provide an update or a
discussion of any other developments subsequent to the original filing.



















                                       2


Item 3.  Controls and Procedures


(a)      Evaluation of disclosure controls and procedures.

         Under the supervision and with the  participation of certain members of
Natural Gas'  management,  the chief  executive  officer and the chief financial
officer  evaluated  the  effectiveness  of  the  design  and  operation  of  the
disclosure  controls and procedures (as defined in Rules 13a-15(e) and 15d-15(e)
of the  Securities  Exchange Act of 1934,  as amended (the  "Exchange  Act")) of
Natural Gas  Services  Group,  Inc. as of the end of the period  covered by this
report.  Based  on this  evaluation,  the  chief  executive  officer  and  chief
financial  officer  concluded  that, as of the end of the period covered by this
report, Natural Gas' disclosure controls and procedures were effective to ensure
that information required to be disclosed by Natural Gas Services Group, Inc. in
the reports  that it files under the Exchange Act is  collected,  processed  and
disclosed within the time periods specified n the Commission's rules and forms.

(b)      Changes in internal controls.

         There  were no changes in Natural  Gas'  internal  controls  during the
period  covered by this report that have  materially  affected or are reasonably
likely to  materially  affect  Natural Gas'  internal  controls  over  financial
reporting.  In addition,  to the  knowledge of the chief  executive  officer and
chief  financial  officer  there  were no changes  in other  factors  that could
significantly  affect these  controls  subsequent to the date of the most recent
evaluation made by the chief executive officer and chief financial officer.

















                                       3


                           PART II - OTHER INFORMATION



Item 6.  Exhibits

         The following  exhibits are filed  herewith or  incorporated  herein by
reference, as indicated:

Exhibit No.                                  Description
-----------                                  -----------


    2.1           Purchase and Sale Agreement by and between Hy-Bon  Engineering
                  Company, Inc. and NGE Leasing, Inc. (Incorporated by reference
                  to Exhibit 2.1 of the Registrant's  Current Report on Form 8-K
                  dated  February  28,  2003 and filed with the  Securities  and
                  Exchange Commission on March 6, 2003)
    
    3.1           Articles  of  Incorporation,   as  amended   (Incorporated  by
                  reference to Exhibit 3.1 of the 10QSB filed and dated November
                  10, 2004)
    
    3.2           Bylaws  (Incorporated  by  reference  to  Exhibit  3.4  of the
                  Registrant's   Registration   Statement  on  Form  SB-2,   No.
                  333-88314)
    
    4.1           Form of warrant  certificate  (Incorporated  by  reference  to
                  Exhibit 4.1 of the Registrant's Registration Statement on Form
                  SB-2, No. 333-88314)
    
    4.2           Form of warrant agent agreement  (Incorporated by reference to
                  Exhibit 4.2 of the Registrant's Registration Statement on Form
                  SB-2, No. 333-88314)
    
    4.3           Form  of  lock-up  agreement  (Incorporated  by  reference  to
                  Exhibit 4.3 of the Registrant's Registration Statement on Form
                  SB-2, No. 333-88314)
    
    4.4           Form of  representative's  option for the  purchase  of common
                  stock  (Incorporated  by  reference  to  Exhibit  4.4  of  the
                  Registrant's   Registration   Statement  on  Form  SB-2,   No.
                  333-88314)
    
    4.5           Form of  representative's  option for the purchase of warrants
                  (Incorporated  by reference to Exhibit 4.5 of the Registrant's
                  Registration Statement on Form SB-2, No. 333-88314)
    
    4.6           Stockholders  Agreement,  dated  January 3, 2005 among Paul D.
                  Hensley,  Tony Vohjesus,  Jim Hazlett and Natural Gas Services
                  Group,  Inc.  (Incorporated by reference to Exhibit 4.3 of the
                  Registrant's From 8-K Report,  dated January 3, 2005, as filed
                  with the  Securities  and  Exchange  Commission  on January 7,
                  2005)
                     


                                       4

                                                   
                  Executive  Compensation Plans and Arrangements (Exhibits 10.1,
                  10.24, 10.25 and 10.26)
    
    10.1          1998 Stock Option Plan  (Incorporated  by reference to Exhibit
                  10.1 of the Registrant's  Registration Statement on Form SB-2,
                  No. 333-88314)
    
    10.2          Asset Purchase  Agreement,  dated January 1, 2001, between the
                  Registrant and Great Lakes Compression,  Inc. (Incorporated by
                  reference  to Exhibit  10.2 of the  Registrant's  Registration
                  Statement on Form SB-2, No. 333-88314)
    
    10.3          Exhibits  3(c)(1),  3(c)(2),   3(c)(3),   3(c)(4),   13(d)(1),
                  13(d)(2)  and  13(d)(3)  to Asset  Purchase  Agreement,  dated
                  January  1,  2001,  between  the  Registrant  and Great  Lakes
                  Compression,  Inc. (Incorporated by reference to Exhibit 10.14
                  of the Registrant's  Registration  Statement on Form SB-2, No.
                  333-88314)
    
    10.4          Amendment to Guaranty  Agreement  between Natural Gas Services
                  Group, Inc. and Dominion Michigan  Production  Services,  Inc.
                  (Incorporated by reference to Exhibit 10.3 of the Registrant's
                  Registration Statement on Form SB-2, No. 333-88314)
    
    10.5          Form of Series A 10% Subordinated  Notes due December 31, 2006
                  (Incorporated by reference to Exhibit 10.8 of the Registrant's
                  Registration Statement on Form SB-2, No. 333-88314)
    
    10.6          Form  of   Five-Year   Warrants  to  Purchase   Common   Stock
                  (Incorporated by reference to Exhibit 10.9 of the Registrant's
                  Registration Statement on Form SB-2, No. 333-88314)
    
    10.7          Warrants issued to Berry-Shino Securities,  Inc. (Incorporated
                  by reference to Exhibit 10.10 of the Registrant's Registration
                  Statement on Form SB-2, No. 333-88314)
    
    10.8          Warrants   issued   to   Neidiger,    Tucker,   Bruner,   Inc.
                  (Incorporated   by   reference   to   Exhibit   10.11  of  the
                  Registrant's   Registration   Statement  on  Form  SB-2,   No.
                  333-88314)
    
    10.9          Form of  warrant  issued in March 2001 for  guaranteeing  debt
                  (Incorporated   by   reference   to   Exhibit   10.12  of  the
                  Registrant's   Registration   Statement  on  Form  SB-2,   No.
                  333-88314)
    
    10.10         Form of  warrant  issued in April 2002 for  guaranteeing  debt
                  (Incorporated   by   reference   to   Exhibit   10.13  of  the
                  Registrant's   Registration   Statement  on  Form  SB-2,   No.
                  333-88314)
    



                                       5


    10.11         Articles of Organization of Hy-Bon Rotary Compression, L.L.C.,
                  dated April 17, 2000  (Incorporated  by  reference  to Exhibit
                  10.18 of the Registrant's Registration Statement on Form SB-2,
                  No. 333-88314)
    
    10.12         Regulations of Hy-Bon Rotary Compression, L.L.C. (Incorporated
                  by reference to Exhibit 10.19 of the Registrant's Registration
                  Statement on Form SB-2, No. 333-88314)
    
    10.13         First  Amended  and  Restated  Loan   Agreement   between  the
                  Registrant  and  Western   National  Bank   (Incorporated   by
                  reference to Exhibit 10.1 of the  Registrant's  Current Report
                  on  Form  8-K,  dated  March  27,  2003  and  filed  with  the
                  Securities and Exchange Commission on April 14, 2003)
    
    10.14         Form of Termination of Employment Agreement Letter relating to
                  the  Employment  Agreement  of  Alan  Kurus  (Incorporated  by
                  reference to Exhibit 10.25 of the  Registrant's  Annual Report
                  on Form 10-KSB for the fiscal year ended December 31, 2002)
    
    10.15         Form of Termination of Employment Agreement Letter relating to
                  the  Employment  Agreement  of Wayne Vinson  (Incorporated  by
                  reference to Exhibit 10.26 of the  Registrant's  Annual Report
                  on Form 10-KSB for the fiscal year ended December 31, 2002)
    
    10.16         Form of Termination of Employment Agreement Letter relating to
                  the  Employment   Agreement  of  Earl  Wait  (Incorporated  by
                  reference to Exhibit 10.27 of the  Registrant's  Annual Report
                  on Form 10-KSB for the fiscal year ended December 31, 2002)
    
    10.17         Triple Net Lease  Agreement,  dated June 1, 2003,  between NGE
                  Leasing, Inc. and Steven J. & Katherina L. Winer (Incorporated
                  by  reference  to  Exhibit  10.17 of the  Registrant's  Annual
                  Report on Form 10-KSB for the fiscal year ended  December  31,
                  2003)
    
    10.18         Lease  Agreement,  dated June 19,  2003,  between NGE Leasing,
                  Inc. and Wise Commercial Properties (Incorporated by reference
                  to Exhibit  10.18 of the  Registrant's  Annual  Report on Form
                  10-KSB for the fiscal year ended December 31, 2003)
    
    10.19         Lease Agreement,  dated March 1, 2004,  between the Registrant
                  and the City of Midland,  Texas  (Incorporated by reference to
                  Exhibit 10.19 of the  Registrant's  Form 10-QSB for the fiscal
                  quarter ended June 30, 2004)
    
    10.20         Second Amended and Restated Loan Agreement,  dated November 3,
                  2003,   between  the  Registrant  and  Western  National  Bank
                  (Incorporated   by   reference   to   Exhibit   10.20  of  the
                  Registrant's Form 10-QSB for the fiscal quarter ended June 30,
                  2004)  



                                       6


    10.21         Securities  Purchase  Agreement,  dated July 20, 2004, between
                  the Registrant and CBarney Investments,  Ltd. (Incorporated by
                  reference to Exhibit 4.1 of the Registrant's Current Report on
                  Form 8-K dated July 20, 2004 and filed with the Securities and
                  Exchange Commission on July 27, 2004)
    
    10.22         Stock Purchase Agreement, dated October 18, 2004, by and among
                  the  Registrant,  Screw  Compression  Systems,  Inc.,  Paul D.
                  Hensley,  Jim  Hazlett  and  Tony  Vohjesus  (Incorporated  by
                  reference to Exhibit 4.1 of the Registrant's Current Report on
                  Form 8-K dated October 18, 2004 and filed with the  Securities
                  and Exchange Commission on October 21, 2004)
    
    10.23         Fourth  Amended and Restated Loan Agreement  (Incorporated  by
                  reference to Exhibit 10.1 of the  Registrant's  Current Report
                  on Form 8-K, dated March 14, 2005 as filed with the Securities
                  and Exchange Commission on March 18, 2005)
    
    10.24         Employment  Agreement  between Paul D. Hensley and Natural Gas
                  Services  Group,  Inc.  (Incorporated  by reference to Exhibit
                  10.1 of the  Registrants  Form 8-K  Report,  dated  January 3,
                  2005, as filed with the Securities and Exchange  Commission on
                  January 7, 2005)
    
    10.25         Employment Agreement between William R. Larkin and Natural Gas
                  Services  Group,  Inc.  (Incorporated  by reference to Exhibit
                  10.25 of the  Registrant's  Form  10-KSB for the  fiscal  year
                  ended  December 31, 2004,  and filed with the  Securities  and
                  Exchange Commission on March 30, 2005)
    
    10.26         Promissory  Note,  dated  January  3,  2005,  in the  original
                  principal amount of $2,100,000.00 made by Natural Gas Services
                  Group,  Inc.  payable  to Paul  D.  Hensley  (Incorporated  by
                  reference to Exhibit 10.26 of the Registrant's Form 10-KSB for
                  the fiscal year ended  December 31,  2004,  and filed with the
                  Securities and Exchange Commission on March 30, 2005)
    
    10.27         Third Amended and Restated Loan Agreement, dated as of January
                  3,  2005,  among  Natural  Gas  Services  Group,  Inc.,  Screw
                  Compression   Systems,   Inc.   and  Western   National   Bank
                  (Incorporated by reference to Exhibit 10.1 of the Registrant's
                  current  Report on form 8-K,  dated January 3, 2005, and filed
                  with the  Securities  and  Exchange  Commission  on January 7,
                  2005)
    
    10.28         Modification  Agreement,  dated as of January 3, 2005,  by and
                  between Natural Gas Services Group,  Inc. and Western National
                  Bank  (Incorporated  by  reference  to  Exhibit  10.2  of  the
                  Registrant's  Current  Report on Form 8-K,  dated  January  3,
                  2005, and filed with the Securities and Exchange Commission on
                  January 7, 2005)
    



                                       7


    10.29         Guaranty  Agreement,  dated as of  January  3,  2005,  made by
                  Natural Gas Service  Group,  Inc.,  for the benefit of Western
                  National  Bank  (Incorporated  by reference to Exhibit 10.3 of
                  the Registrant's  Current Report on Form 8-K, dated January 3,
                  2005, and filed with the Securities and Exchange Commission on
                  January 7, 2005)
    
    10.30         Guaranty Agreement, dated as of January 3, 2005, made by Screw
                  Compression Systems, Inc., for the benefit of Western National
                  Bank  (Incorporated  by  reference  to  Exhibit  10.4  of  the
                  Registrant's  Current  Report on Form 8-K,  dated  January  3,
                  2005, and filed with the Securities and Exchange Commission on
                  January 7, 2005)
    
    10.31         Third Amended and Restated  Loan  Agreement  (Incorporated  by
                  reference to Exhibit 10.1 of the  Registrant's  Form 8-K dated
                  January 3, 2005 and filed  with the  Securities  and  Exchange
                  Commission January 3, 2005)
    
    10.32         First   Modification  to  Fourth  Amended  and  Restated  Loan
                  Agreement  (Incorporated  by  reference to Exhibit 10.1 of the
                  Registrant's  Form  8-K  dated  May 1,  2005  and  filed  with
                  Securities and Exchange Commission May 13, 2005)
    
    14.0          Code of Ethics  (Incorporated  by reference to Exhibit 14.0 of
                  the  Registrant's  Form  10-KSB  for  the  fiscal  year  ended
                  December 31, 2004,  and filed with the Securities and Exchange
                  Commission on March 30, 2005)
    
    21.0          Subsidiaries (Incorporated by reference to Exhibit 21.0 of the
                  Registrant's  Form 10-KSB for the fiscal  year ended  December
                  31,  2004,   and  filed  with  the   Securities  and  Exchange
                  Commission on March 30, 2005)
    
    
    *31.1         Certification  of Chief Executive  Officer required by Section
                  302 of the Sarbanes-Oxley Act of 2002
    
    *31.2         Certification  of Chief Financial  Officer required by Section
                  302 of the Sarbanes-Oxley Act of 2002
    
    *32.1         Certification  required by Section  906 of the  Sarbanes-Oxley
                  Act of 2002
    
    *32.2         Certification  required by Section  906 of the  Sarbanes-Oxley
                  Act of 2002
----------------------------- 
 * Filed herewith.



                                       8


                                   SIGNATURES

         In accordance with the requirements of the Exchange Act, the registrant
caused this report to be signed on its behalf by the undersigned, thereunto duly
authorized.


                                        NATURAL GAS SERVICES GROUP, INC.


                                        By: /s/ Stephen C. Taylor               
                                           -------------------------------------
                                           Stephen C. Taylor
                                           President and Chief Executive Officer

                                        By:  /s/ Earl R. Wait                   
                                           -------------------------------------
                                           Earl R. Wait
                                           Chief Financial Officer and Treasurer

                                        July 6, 2005
















                                       9


                                INDEX TO EXHIBITS



Exhibit No.                                  Description
-----------                                  -----------


    2.1           Purchase and Sale Agreement by and between Hy-Bon  Engineering
                  Company, Inc. and NGE Leasing, Inc. (Incorporated by reference
                  to Exhibit 2.1 of the Registrant's  Current Report on Form 8-K
                  dated  February  28,  2003 and filed with the  Securities  and
                  Exchange Commission on March 6, 2003)
    
    3.1           Articles  of  Incorporation,   as  amended   (Incorporated  by
                  reference to Exhibit 3.1 of the 10QSB filed and dated November
                  10, 2004)
    
    3.2           Bylaws  (Incorporated  by  reference  to  Exhibit  3.4  of the
                  Registrant's   Registration   Statement  on  Form  SB-2,   No.
                  333-88314)
    
    4.1           Form of warrant  certificate  (Incorporated  by  reference  to
                  Exhibit 4.1 of the Registrant's Registration Statement on Form
                  SB-2, No. 333-88314)
    
    4.2           Form of warrant agent agreement  (Incorporated by reference to
                  Exhibit 4.2 of the Registrant's Registration Statement on Form
                  SB-2, No. 333-88314)
    
    4.3           Form  of  lock-up  agreement  (Incorporated  by  reference  to
                  Exhibit 4.3 of the Registrant's Registration Statement on Form
                  SB-2, No. 333-88314)
    
    4.4           Form of  representative's  option for the  purchase  of common
                  stock  (Incorporated  by  reference  to  Exhibit  4.4  of  the
                  Registrant's   Registration   Statement  on  Form  SB-2,   No.
                  333-88314)
    
    4.5           Form of  representative's  option for the purchase of warrants
                  (Incorporated  by reference to Exhibit 4.5 of the Registrant's
                  Registration Statement on Form SB-2, No. 333-88314)
    
    4.6           Stockholders  Agreement,  dated  January 3, 2005 among Paul D.
                  Hensley,  Tony Vohjesus,  Jim Hazlett and Natural Gas Services
                  Group,  Inc.  (Incorporated by reference to Exhibit 4.3 of the
                  Registrant's From 8-K Report,  dated January 3, 2005, as filed
                  with the  Securities  and  Exchange  Commission  on January 7,
                  2005)
                                                   
                  Executive  Compensation Plans and Arrangements (Exhibits 10.1,
                  10.24, 10.25 and 10.26)
    


                                      


    10.1          1998 Stock Option Plan  (Incorporated  by reference to Exhibit
                  10.1 of the Registrant's  Registration Statement on Form SB-2,
                  No. 333-88314)
    
    10.2          Asset Purchase  Agreement,  dated January 1, 2001, between the
                  Registrant and Great Lakes Compression,  Inc. (Incorporated by
                  reference  to Exhibit  10.2 of the  Registrant's  Registration
                  Statement on Form SB-2, No. 333-88314)
    
    10.3          Exhibits  3(c)(1),  3(c)(2),   3(c)(3),   3(c)(4),   13(d)(1),
                  13(d)(2)  and  13(d)(3)  to Asset  Purchase  Agreement,  dated
                  January  1,  2001,  between  the  Registrant  and Great  Lakes
                  Compression,  Inc. (Incorporated by reference to Exhibit 10.14
                  of the Registrant's  Registration  Statement on Form SB-2, No.
                  333-88314)
    
    10.4          Amendment to Guaranty  Agreement  between Natural Gas Services
                  Group, Inc. and Dominion Michigan  Production  Services,  Inc.
                  (Incorporated by reference to Exhibit 10.3 of the Registrant's
                  Registration Statement on Form SB-2, No. 333-88314)
    
    10.5          Form of Series A 10% Subordinated  Notes due December 31, 2006
                  (Incorporated by reference to Exhibit 10.8 of the Registrant's
                  Registration Statement on Form SB-2, No. 333-88314)
    
    10.6          Form  of   Five-Year   Warrants  to  Purchase   Common   Stock
                  (Incorporated by reference to Exhibit 10.9 of the Registrant's
                  Registration Statement on Form SB-2, No. 333-88314)
    
    10.7          Warrants issued to Berry-Shino Securities,  Inc. (Incorporated
                  by reference to Exhibit 10.10 of the Registrant's Registration
                  Statement on Form SB-2, No. 333-88314)
    
    10.8          Warrants   issued   to   Neidiger,    Tucker,   Bruner,   Inc.
                  (Incorporated   by   reference   to   Exhibit   10.11  of  the
                  Registrant's   Registration   Statement  on  Form  SB-2,   No.
                  333-88314)
    
    10.9          Form of  warrant  issued in March 2001 for  guaranteeing  debt
                  (Incorporated   by   reference   to   Exhibit   10.12  of  the
                  Registrant's   Registration   Statement  on  Form  SB-2,   No.
                  333-88314)
    
    10.10         Form of  warrant  issued in April 2002 for  guaranteeing  debt
                  (Incorporated   by   reference   to   Exhibit   10.13  of  the
                  Registrant's   Registration   Statement  on  Form  SB-2,   No.
                  333-88314)
    
    10.11         Articles of Organization of Hy-Bon Rotary Compression, L.L.C.,
                  dated April 17, 2000  (Incorporated  by  reference  to Exhibit
                  10.18 of the Registrant's Registration Statement on Form SB-2,
                  No. 333-88314)
    



    10.12         Regulations of Hy-Bon Rotary Compression, L.L.C. (Incorporated
                  by reference to Exhibit 10.19 of the Registrant's Registration
                  Statement on Form SB-2, No. 333-88314)
    
    10.13         First  Amended  and  Restated  Loan   Agreement   between  the
                  Registrant  and  Western   National  Bank   (Incorporated   by
                  reference to Exhibit 10.1 of the  Registrant's  Current Report
                  on  Form  8-K,  dated  March  27,  2003  and  filed  with  the
                  Securities and Exchange Commission on April 14, 2003)
    
    10.14         Form of Termination of Employment Agreement Letter relating to
                  the  Employment  Agreement  of  Alan  Kurus  (Incorporated  by
                  reference to Exhibit 10.25 of the  Registrant's  Annual Report
                  on Form 10-KSB for the fiscal year ended December 31, 2002)
    
    10.15         Form of Termination of Employment Agreement Letter relating to
                  the  Employment  Agreement  of Wayne Vinson  (Incorporated  by
                  reference to Exhibit 10.26 of the  Registrant's  Annual Report
                  on Form 10-KSB for the fiscal year ended December 31, 2002)
    
    10.16         Form of Termination of Employment Agreement Letter relating to
                  the  Employment   Agreement  of  Earl  Wait  (Incorporated  by
                  reference to Exhibit 10.27 of the  Registrant's  Annual Report
                  on Form 10-KSB for the fiscal year ended December 31, 2002)
    
    10.17         Triple Net Lease  Agreement,  dated June 1, 2003,  between NGE
                  Leasing, Inc. and Steven J. & Katherina L. Winer (Incorporated
                  by  reference  to  Exhibit  10.17 of the  Registrant's  Annual
                  Report on Form 10-KSB for the fiscal year ended  December  31,
                  2003)
    
    10.18         Lease  Agreement,  dated June 19,  2003,  between NGE Leasing,
                  Inc. and Wise Commercial Properties (Incorporated by reference
                  to Exhibit  10.18 of the  Registrant's  Annual  Report on Form
                  10-KSB for the fiscal year ended December 31, 2003)
    
    10.19         Lease Agreement,  dated March 1, 2004,  between the Registrant
                  and the City of Midland,  Texas  (Incorporated by reference to
                  Exhibit 10.19 of the  Registrant's  Form 10-QSB for the fiscal
                  quarter ended June 30, 2004)
    
    10.20         Second Amended and Restated Loan Agreement,  dated November 3,
                  2003,   between  the  Registrant  and  Western  National  Bank
                  (Incorporated   by   reference   to   Exhibit   10.20  of  the
                  Registrant's Form 10-QSB for the fiscal quarter ended June 30,
                  2004)  

    10.21         Securities  Purchase  Agreement,  dated July 20, 2004, between
                  the Registrant and CBarney Investments,  Ltd. (Incorporated by
                  reference to Exhibit 4.1 of the Registrant's Current Report on
                  Form 8-K dated July 20, 2004 and filed with the Securities and
                  Exchange Commission on July 27, 2004)
    



    10.22         Stock Purchase Agreement, dated October 18, 2004, by and among
                  the  Registrant,  Screw  Compression  Systems,  Inc.,  Paul D.
                  Hensley,  Jim  Hazlett  and  Tony  Vohjesus  (Incorporated  by
                  reference to Exhibit 4.1 of the Registrant's Current Report on
                  Form 8-K dated October 18, 2004 and filed with the  Securities
                  and Exchange Commission on October 21, 2004)
    
    10.23         Fourth  Amended and Restated Loan Agreement  (Incorporated  by
                  reference to Exhibit 10.1 of the  Registrant's  Current Report
                  on Form 8-K, dated March 14, 2005 as filed with the Securities
                  and Exchange Commission on March 18, 2005)
    
    10.24         Employment  Agreement  between Paul D. Hensley and Natural Gas
                  Services  Group,  Inc.  (Incorporated  by reference to Exhibit
                  10.1 of the  Registrants  Form 8-K  Report,  dated  January 3,
                  2005, as filed with the Securities and Exchange  Commission on
                  January 7, 2005)
    
    10.25         Employment Agreement between William R. Larkin and Natural Gas
                  Services  Group,  Inc.  (Incorporated  by reference to Exhibit
                  10.25 of the  Registrant's  Form  10-KSB for the  fiscal  year
                  ended  December 31, 2004,  and filed with the  Securities  and
                  Exchange Commission on March 30, 2005)
    
    10.26         Promissory  Note,  dated  January  3,  2005,  in the  original
                  principal amount of $2,100,000.00 made by Natural Gas Services
                  Group,  Inc.  payable  to Paul  D.  Hensley  (Incorporated  by
                  reference to Exhibit 10.26 of the Registrant's Form 10-KSB for
                  the fiscal year ended  December 31,  2004,  and filed with the
                  Securities and Exchange Commission on March 30, 2005)
    
    10.27         Third Amended and Restated Loan Agreement, dated as of January
                  3,  2005,  among  Natural  Gas  Services  Group,  Inc.,  Screw
                  Compression   Systems,   Inc.   and  Western   National   Bank
                  (Incorporated by reference to Exhibit 10.1 of the Registrant's
                  current  Report on form 8-K,  dated January 3, 2005, and filed
                  with the  Securities  and  Exchange  Commission  on January 7,
                  2005)
    
    10.28         Modification  Agreement,  dated as of January 3, 2005,  by and
                  between Natural Gas Services Group,  Inc. and Western National
                  Bank  (Incorporated  by  reference  to  Exhibit  10.2  of  the
                  Registrant's  Current  Report on Form 8-K,  dated  January  3,
                  2005, and filed with the Securities and Exchange Commission on
                  January 7, 2005)
    


    10.29         Guaranty  Agreement,  dated as of  January  3,  2005,  made by
                  Natural Gas Service  Group,  Inc.,  for the benefit of Western
                  National  Bank  (Incorporated  by reference to Exhibit 10.3 of
                  the Registrant's  Current Report on Form 8-K, dated January 3,
                  2005, and filed with the Securities and Exchange Commission on
                  January 7, 2005)
    
    10.30         Guaranty Agreement, dated as of January 3, 2005, made by Screw
                  Compression Systems, Inc., for the benefit of Western National
                  Bank  (Incorporated  by  reference  to  Exhibit  10.4  of  the
                  Registrant's  Current  Report on Form 8-K,  dated  January  3,
                  2005, and filed with the Securities and Exchange Commission on
                  January 7, 2005)
    
    10.31         Third Amended and Restated  Loan  Agreement  (Incorporated  by
                  reference to Exhibit 10.1 of the  Registrant's  Form 8-K dated
                  January 3, 2005 and filed  with the  Securities  and  Exchange
                  Commission January 3, 2005)
    
    10.32         First   Modification  to  Fourth  Amended  and  Restated  Loan
                  Agreement  (Incorporated  by  reference to Exhibit 10.1 of the
                  Registrant's  Form  8-K  dated  May 1,  2005  and  filed  with
                  Securities and Exchange Commission May 13, 2005)
    
    14.0          Code of Ethics  (Incorporated  by reference to Exhibit 14.0 of
                  the  Registrant's  Form  10-KSB  for  the  fiscal  year  ended
                  December 31, 2004,  and filed with the Securities and Exchange
                  Commission on March 30, 2005)
    
    21.0          Subsidiaries (Incorporated by reference to Exhibit 21.0 of the
                  Registrant's  Form 10-KSB for the fiscal  year ended  December
                  31,  2004,   and  filed  with  the   Securities  and  Exchange
                  Commission on March 30, 2005)
    
    
    *31.1         Certification  of Chief Executive  Officer required by Section
                  302 of the Sarbanes-Oxley Act of 2002
    
    *31.2         Certification  of Chief Financial  Officer required by Section
                  302 of the Sarbanes-Oxley Act of 2002
    
    *32.1         Certification  required by Section  906 of the  Sarbanes-Oxley
                  Act of 2002
    
    *32.2         Certification  required by Section  906 of the  Sarbanes-Oxley
                  Act of 2002
----------------------------- 
 * Filed herewith.