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


                                    FORM 8-K


                 CURRENT REPORT PURSUANT TO SECTION 13 OR 15(d)
                     OF THE SECURITIES EXCHANGE ACT OF 1934


         Date of Report (Date of earliest event reported): May 10, 2005


                        NATURAL GAS SERVICES GROUP, INC.
             (Exact Name of Registrant as Specified in Its Charter)



              Colorado                      1-31398               75-2811855
  (State or other jurisdiction          (Commission File        (IRS Employer
of  Incorporation or organization)          Number)          Identification No.)


2911 South County Road 1260 Midland, Texas                         79706
 (Address of Principal Executive Offices)                        (Zip Code)


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


                                 Not Applicable
          (Former name or former address, if changed since last report)


Check  the  appropriate  box  below  if the  Form  8-K  filing  is  intended  to
simultaneously  satisfy the filing obligation of the registrant under any of the
following provisions:

[_]      Written  communications  pursuant to Rule 425 under the  Securities Act
         (17 CFR 230.425)

[_]      Soliciting  material pursuant to Rule 14a-12 under the Exchange Act (17
         CFR 240.14a-12)

[_]      Pre-commencement  communications  pursuant to Rule  14d-2(b)  under the
         Exchange Act (17 CFR 240.14d-2(b))

[_]      Pre-commencement  communications  pursuant to Rule  13e-4(c)  under the
         Exchange Act (17 CFR 240.13e-4(c))




Item 1.01.        Entry into a Material Definitive Agreement.

         On May 10, 2005,  Natural Gas Services  Group,  Inc., as borrower,  and
Western  National Bank, as lender,  entered into a First  Modification to Fourth
Amended and  Restated  Loan  Agreement,  dated  effective as of May 1, 2005 (the
"Loan  Modification  Agreement").  The Loan  Modification  Agreement  amends the
"Consolidated  Current Ratio" definition in the Fourth Amended and Restated Loan
Agreement, dated March 14, 2005 (the "Loan Agreement"),  between Natural Gas and
Western National Bank, by expanding the assets  considered in the calculation of
such ratio to include  restricted  cash held by Natural Gas. In addition,  under
the Loan  Modification  Agreement,  we are  required to maintain a  Consolidated
Current  Ratio  of 1.4 to  1.00  from  month  to  month,  versus  1.5 to 1.00 as
originally required under the Loan Agreement.

         As previously  reported,  the  indebtedness  extended to Natural Gas by
Western  National  Bank under the Loan  Agreement is evidenced by the  following
promissory notes (collectively, the "Notes"):

         (1) Multiple Advance Term Promissory Note, dated March 14, 2005, in the
         original  principal  amount of  $1,500,000.00,  payable by Natural  Gas
         Services  Group,  Inc. to the order of Western  National Bank,  bearing
         interest at a current annual rate of 7.00%and maturing on April 1, 2010
         (the "$1,500,000.00 Multiple Advance Term Note");

         (2) Multiple Advance Term Promissory Note, dated March 14, 2005, in the
         original  principal  amount of  $10,000,000.00,  payable by Natural Gas
         Services  Group,  Inc. to the order of Western  National Bank,  bearing
         interest  at a current  annual  rate of 7.00% and  maturing on April 1,
         2011 ($10,000,000.00 Multiple Advance Term Note");

         (3) Term  Promissory  Note,  dated  January  3, 2005,  in the  original
         principal  amount of  $8,000,000.00,  payable by Natural  Gas  Services
         Group, Inc. to the order of Western National Bank,  bearing interest at
         a current  annual  rate of 7.00% and  maturing on January 1, 2012 ("the
         $8,000,000.00 Term Note");

         (4) Revolving Line of Credit Promissory Note, dated January 3, 2005, in
         the original principal amount of $2,000,000.00,  payable by Natural Gas
         Services  Group,  Inc. to the order of Western  National Bank,  bearing
         interest at a current  annual rate of 7.00% and  maturing on January 1,
         2006 (the "Revolving Line of Credit Note");

         (5) Term  Promissory  Note,  dated  November 3, 2003,  in the  original
         principal  amount of  $7,521,109.00,  payable by Natural  Gas  Services
         Group, Inc. to the order of Western National Bank,  bearing interest at
         a current  annual rate of 7.00% and maturing on September  15, 2007, as
         modified  in a  Modification  Agreement,  dated  January  3,  2005 (the
         "$7,521,109.00 Term Note");

         (6) Advancing Line of Credit  Promissory  Note, dated November 3, 2003,
         in the original principal amount of $10,000,000.00,  payable by Natural
         Gas Services Group, Inc. to the order of Western National Bank, bearing
         interest at a current annual rate of 7.00% and maturing on November 15,
         2009, as modified in a Modification Agreement,  dated December 15, 2004
         (the "Advancing Line of Credit Note"); and




         (7) Term  Promissory  Note,  dated  January  3, 2005,  in the  original
         principal  amount  of  $1,415,836.00,   payable  by  Screw  Compression
         Systems,  Inc. to the order of Western National Bank,  bearing interest
         at a current  annual rate of 7.00% and maturing on January 1, 2010 (the
         $1,415,836,00 Term Note").

         Concurrently   with  the  our   execution  and  delivery  of  the  Loan
Modification  Agreement,  we also entered into the following  note  modification
agreements (collectively, the "Note Modification Agreements"):

         (1) Modification  Agreement,  dated effective as of May 1, 2005, by and
         between  Natural Gas Services  Group,  Inc. and Western  National Bank,
         modifying the $1,500,000.00 Multiple Advance Term Note;

         (2) Modification  Agreement,  dated effective as of May 1, 2005, by and
         between  Natural Gas Services  Group,  Inc. and Western  National Bank,
         modifying the $10,000,000.00 Multiple Advance Term Note;

         (3) Modification  Agreement,  dated effective as of May 1, 2005, by and
         between  Natural Gas Services  Group,  Inc. and Western  National Bank,
         modifying the $8,000,000.00 Term Note;

         (4) Modification  Agreement,  dated effective as of May 1, 2005, by and
         between  Natural Gas Services  Group,  Inc. and Western  National Bank,
         modifying the Revolving Line of Credit Note;

         (5) Second Modification  Agreement,  dated effective as of May 1, 2005,
         by and between  Natural Gas Services Group,  Inc. and Western  National
         Bank, modifying the $7,521,109.00 Term Note;

         (6) Second Modification  Agreement,  dated effective as of May 1, 2005,
         by and between  Natural Gas Services Group,  Inc. and Western  National
         Bank, modifying the Advancing Line of Credit Note; and

         (7) Modification Agreement, dated effective as of May 1, 2005, by and
         between Natural Gas Services Group, Inc. and Western National Bank,
         modifying the $1,415,836.00 Term Note.

Under the Note Modification Agreements, the annual rate at which each Note bears
interest was reduced by 0.50%, and with the exception of the $7,521,109.00  Term
Note and the  Advancing  Line of Credit  Note,  the floor  rate of each Note was
reduced from 6.25% to 6.00%. The floor rate of the  $7,521,109.00  Term Note and
the Advancing Line of Credit Note remains at 5.25%.

         The remaining  terms and provisions of the Loan Agreement and the Notes
remain in full force and effect.




Item 9.01         Financial Statements and Exhibits.


         (c)      Exhibits.

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


                    *10.1           First  Modification  to Fourth  Amended  and
                                    Restated Loan Agreement,  dated effective as
                                    of May 1,  2005,  by and among  Natural  Gas
                                    Services  Group,  Inc. and Western  National
                                    Bank.

                    *10.2           Modification  Agreement,  dated effective as
                                    of May 1, 2005,  by and between  Natural Gas
                                    Services  Group,  Inc. and Western  National
                                    Bank.

                    *10.3           Modification  Agreement,  dated effective as
                                    of May 1, 2005,  by and between  Natural Gas
                                    Services  Group,  Inc. and Western  National
                                    Bank.

                    *10.4           Modification  Agreement,  dated effective as
                                    of May 1, 2005,  by and between  Natural Gas
                                    Services  Group,  Inc. and Western  National
                                    Bank.

                    *10.5           Modification  Agreement,  dated effective as
                                    of May 1, 2005,  by and between  Natural Gas
                                    Services  Group,  Inc. and Western  National
                                    Bank.

                    *10.6           Second   Modification    Agreement,    dated
                                    effective as of May 1, 2005,  by and between
                                    Natural Gas Services Group, Inc. and Western
                                    National Bank.

                    *10.7           Second   Modification    Agreement,    dated
                                    effective as of May 1, 2005,  by and between
                                    Natural Gas Services Group, Inc. and Western
                                    National Bank.

                    *10.8           Modification  Agreement,  dated effective as
                                    of May 1, 2005,  by and between  Natural Gas
                                    Services  Group,  Inc. and Western  National
                                    Bank.
              ---------------------
              *  Filed herewith




                                   SIGNATURES


         Pursuant to the  requirements  of the Securities  Exchange Act of 1934,
the  Registrant  has duly  caused  this report to be signed on its behalf by the
undersigned hereunto duly authorized.


                                                NATURAL GAS SERVICES GROUP, INC.


                                                By: /s/ Stephen C. Taylor      
                                                   -----------------------------
                                                   Stephen C. Taylor, President


Dated: May 10, 2005



                                  EXHIBIT INDEX

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


   *10.1          First   Modification  to  Fourth  Amended  and  Restated  Loan
                  Agreement,  dated  effective  as May  1,  2005,  by and  among
                  Natural Gas Services Group, Inc. and Western National Bank.

   *10.2          Modification Agreement,  dated effective as of May 1, 2005, by
                  and  between  Natural Gas  Services  Group,  Inc.  and Western
                  National Bank.
   
   *10.3          Modification Agreement,  dated effective as of May 1, 2005, by
                  and  between  Natural Gas  Services  Group,  Inc.  and Western
                  National Bank.
   
   *10.4          Modification Agreement,  dated effective as of May 1, 2005, by
                  and  between  Natural Gas  Services  Group,  Inc.  and Western
                  National Bank.
   
   *10.5          Modification Agreement,  dated effective as of May 1, 2005, by
                  and  between  Natural Gas  Services  Group,  Inc.  and Western
                  National Bank.
   
   *10.6          Second  Modification  Agreement,  dated effective as of May 1,
                  2005,  by and between  Natural Gas  Services  Group,  Inc. and
                  Western National Bank.
   
   *10.7          Second  Modification  Agreement,  dated effective as of May 1,
                  2005,  by and between  Natural Gas  Services  Group,  Inc. and
                  Western National Bank.
   
   *10.8          Modification Agreement,  dated effective as of May 1, 2005, by
                  and  between  Natural Gas  Services  Group,  Inc.  and Western
                  National Bank.
---------------------
*  Filed herewith