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

                                  FORM 10-KSB/A

                                (Amendment No. 1)

[X]  ANNUAL REPORT UNDER SECTION 13 OR 15(d) OF THE  SECURITIES  EXCHANGE ACT OF
     1934

                   For the fiscal year ended December 31, 2004

[_]  TRANSITION REPORT UNDER 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.
                 (Name of small business issuer 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) (Zip Code)

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

         Securities registered under Section 12(b) of the Exchange Act:

                           Common Stock $.01 Par Value
                                (Title of Class)


                        Warrants to Purchase Common Stock
                                (Title of Class)

       Securities registered under Section 12(g) of the Exchange Act: None


         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
                                                                      ---   ---

         Check if there is no  disclosure  of  delinquent  filers in response to
Item 405 of  Regulation  S-B contained in this form,  and no disclosure  will be
contained,  to the best of the  registrant's  knowledge,  in definitive proxy or
information statements incorporated by reference in Part III of this Form 10-KSB
or any amendment to this Form 10-KSB. X
                                     ---

         State issuer's revenue for its most recent fiscal year: $15,958,199

         The aggregate  market value of the voting and non-voting  common equity
held by non-affiliates  at March 23, 2005,  computed by reference to the closing
price of $10.76 per share on the American Stock Exchange, was $47,676,914.

         The number of shares  outstanding  of each of the  issuer's  classes of
common equity on March 23, 2005, was 6,765,764.

                       Documents Incorporated by Reference
                                      None

         Transitional Small Business Disclosure Format Yes    No X
                                                          ---   ---


<PAGE>

                                EXPLANATORY NOTE

         Natural Gas Services Group, Inc. is filing this Amendment No. 1 on Form
10-KSB/A to its Annual Report on Form 10-KSB for the fiscal year ended  December
31, 2004,  as filed with the SEC on March 30, 2005,  for the purpose of amending
and  restating in its entirety Item 11 and Item 13 of such Annual Report on Form
10-KSB, as set forth below. As a result of this amendment,  Natural Gas Services
Group,  Inc. is filing as exhibits  to this  Amendment  No. 1 on Form 10-KSB the
certifications  pursuant  to Section  302 and 906 of the  Sarbanes-Oxley  Act of
2002.  This  Amendment  No. 1 on Form  10-KSB/A  does not change our  previously
reported financial statements and other financial disclosures.

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


















                                       2
<PAGE>

Item 11.  SECURITY  OWNERSHIP OF CERTAIN  BENEFICIAL  OWNERS AND  MANAGEMENT AND
          RELATED STOCKHOLDER MATTERS


         The following  table sets forth,  as of March 18, 2005,  the beneficial
ownership  of our common  stock by (i) each of our  directors;  (ii) each of our
executive  officers;  (iii) all of our  executive  officers  and  directors as a
group;  and (iv)  each  person  known by us to  beneficially  own more than five
percent of our common stock.  Except as otherwise  indicated below,  each of the
individuals  named in the table has sole voting and investment  power, or shares
such powers with his spouse,  with respect to the shares set forth  opposite his
name.

                                                                      Percent
                Name and                Shares of Common Stock      Beneficially
                Address                   Beneficially Owned           Owned
------------------------------------    ----------------------      ------------

Wallace O. Sellers                            693,159(1)               10.2%
P.O. Box 106
6539 Upper York Road
Solebury, Pennsylvania  18963-0106

Charles G. Curtis                              80,500(2)                1.2%
1 Penrose Lane
Colorado Springs, Colorado  80906

Paul D. Hensley                               426,829                   6.3%
3005 N. 15th Street
Broken Arrow, Oklahoma  74012

William F. Hughes                             247,000(3)                3.6%
42921 Normandy Lane
Lancaster, California  93536

Wallace C. Sparkman                           167,691(4)                2.5%
4906 Oakwood Court
Midland, Texas  79707

Gene A Strasheim                                8,500(5)                 *
165 Huntington Place
Colorado Springs, Colorado  80906

Richard L. Yadon                              299,183(6)                4.4%
P.O. Box 8715
Midland, Texas  79708-8715

Ron L. Bingham                                  6,000(7)                 *
P.O. Box 945
Lewiston, Michigan  49756




                                       3
<PAGE>

W. Randy Larkin                                12,000(8)                 *
5609 Heartland
Midland, Texas  79707

S. Craig Rogers                                14,250(9)                 *
14732 Bluestem Ave
Gardendale, Texas  79758

Earl R. Wait                                   75,520(10)               1.1%
5102 Teakwood Trace
Midland, Texas  79707

Scott W. Sparkman                             519,467(11)               7.7%
1604 Ventura Ave
Midland, Texas  79705

Charles L. Barney                             936,274(12)              13.4%
952 Echo Lane, Suite 364
Houston, Texas 77024

RWG Investments LLC                           369,000 (13)              5.5%
5980 Wildwood Drive
Rapid City, South Dakota  57902

Babson Capital Management LLC                 651,700(14)               9.6%
One Memorial Drive
Cambridge, Massachusetts 02142-1300

All directors (and nominees) and
executive officers as a group
(12 persons)                                2,550,099 (15)             36.5%

---------------------------------------
 *       Less than one percent.
(1)      Includes  196,091  shares of common stock owned by the Trust under Deed
         of Wallace O. Sellers,  dated June 21, 1991,  196,091  shares of common
         stock owned by the Trust under Deed of Wallace O.  Sellers,  dated June
         22, 1971; options to purchase 2,500 shares of common stock at $3.88 per
         share,  options to purchase  2,500  shares of common stock at $5.55 per
         share,  and options to purchase  2,500  shares of common stock at $9.34
         per share held by Mr. Sellers; and 158,600 shares owned by Mr. Sellers'
         wife.  The  trustee  of each trust is an  unrelated  third  party.  Mr.
         Sellers' wife is a contingent remainder  beneficiary of one trust and a
         beneficiary during her lifetime of the other.
(2)      Includes  options to purchase 2,500 shares of common stock at $3.88 per
         share,  options to purchase  2,500  shares of common stock at $5.55 per
         share,  options to purchase  2,500  shares of common stock at $9.34 per
         share,  and warrants to purchase 40,000 shares of common stock at $3.25
         per share.
(3)      Includes  180,500  shares of common  stock  and a warrant  to  purchase
         60,000  shares of common  stock at $3.25 per share owned by the William
         and Cheryl Hughes Family  Trust,  an option to purchase  2,500 share of
         common stock at $5.55, and an option to purchase 2,500 shares of common
         stock at $9.34.
(4)      Includes  105,691  shares owned by Diamente  Investments,  LLP, a Texas
         limited  partnership  of which Mr.  Sparkman  is a general  and limited
         partner.
(5)      Includes  options to purchase 2,500 shares of common stock at $5.55 per
         share and options to purchase 2,500 shares of common stock at $9.34 per
         share.


                                       4
<PAGE>

(6)      Includes warrants to purchase 9,365 shares of common stock at $2.50 per
         share,  warrants to purchase  5,318 shares of common stock at $3.25 per
         share,  options to purchase  2,500  shares of common stock at $5.55 per
         share and options to purchase 2,500 shares of common stock at $9.34 per
         share.
(7)      Includes an option to purchase  6,000  shares of common  stock at $5.58
         per share.
(8)      Includes an option to purchase  12,000  shares of common stock at $7.50
         per share.
(9)      Includes warrants to purchase 1,125 shares of common stock at $6.25 per
         share and an option to purchase  12,000 shares of common stock at $3.25
         per share.
(10)     Includes an option to purchase  15,000  shares of common stock at $3.25
         per share.
(11)     Includes an option to purchase  3,000  shares of common  stock at $7.50
         per share,  and 475,000 shares of common stock and warrants to purchase
         21,467  shares of common  stock at $2.50 per share  owned by  Diamond S
         DGT, a trust of which Mr.  Sparkman is a co-trustee and  co-beneficiary
         with his sister.
(12)     Based on  Amendment  No. 1 to Schedule  13D filed with the SEC on March
         22,  2005,  Charles  L.  Barney,  the sole  indirect  owner of  CBarney
         Investments,  Ltd.  and  Mark X  Energy  Company,  reported  beneficial
         ownership  of 707,974  shares of common  stock and warrants to purchase
         228,300 shares of common stock.  Mr. Barney  reported shared voting and
         dispositive  power with (i) CBarney  Investments,  Ltd. with respect to
         the 600,674 shares and warrants its owns and (ii) Mark X Energy Company
         with  respect to the 335,600  shares and  warrants it owns,  due to his
         ownership control of those entities.
(13)     Includes a warrant to purchase  15,000  shares of common stock at $6.25
         per share, 245,000 shares of common stock owned by RWG Investments LLC,
         and 82,000 shares of common stock owned by G Five  Development LLC. RWG
         Investments LLC is a limited  liability  company owned solely by Roland
         W. Gentner. G Five Development LLC is a limited liability company,  the
         beneficial owners of which are Roland W. Gentner,  his spouse,  and his
         three sons.
(14)     As  reported  in  Schedule  13G filed with the SEC on February 8, 2005,
         Babson Capital  Management LLC, in its capacity as investment  adviser,
         may be deemed the  beneficial  owner of such shares  which are owned by
         investment  advisory  client(s).  Babson  Capital  reported sole voting
         power with respect to 641,400 shares;  shared voting power with respect
         to 10,300 shares;  and sole  dispositive  power with respect to 651,700
         shares.
(15)     Includes options to purchase 78,000 shares of common stock and warrants
         to purchase 137,275 shares of common stock.







                                       5
<PAGE>

Item 13. EXHIBITS

         The  following  is a list of all  exhibits  filed as part of this  Form
10-KSB/A:

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)



                                       6
<PAGE>

                           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)



                                       7
<PAGE>

   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)



                                       8
<PAGE>

   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)

   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)



                                       9
<PAGE>

   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)

   23.1                    Consent of Hein &  Associates  LLP  (Incorporated  by
                           reference  to Exhibit 23.1 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.












                                       10
<PAGE>

SIGNATURES


         In  accordance  with  Section  13 or 15(d)  of the  Exchange  Act,  the
registrant  caused  this  report to be signed on its behalf by the  undersigned,
thereunto duly authorized.





Date:  May 3, 2005                           NATURAL GAS SERVICES GROUP, INC.



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




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






                                       11
<PAGE>

                                  EXHIBIT INDEX


         The  following  is a list of all  exhibits  filed as part of this  Form
10-KSB/A:

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)

<PAGE>

   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)


<PAGE>

   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)


<PAGE>

    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)

   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)

   23.1                    Consent of Hein &  Associates  LLP  (Incorporated  by
                           reference  to Exhibit 23.1 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


<PAGE>

  *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.