EXHIBIT 10.1


                        FIRST AMENDMENT TO LOAN AGREEMENT
                        ---------------------------------


      Amendment,  dated as of the 24th day of July,  1998,  by and among Michael
Baker  Corporation,  a  Pennsylvania  corporation,  Michael  Baker Jr.,  Inc., a
Pennsylvania corporation, Baker Environmental, Inc., a Pennsylvania corporation,
Baker/MO Services,  Inc., a Texas corporation,  Baker Support Services,  Inc., a
Texas  corporation,  Baker/Mellon  Stuart  Construction,  Inc.,  a  Pennsylvania
corporation,  Baker  Heavy & Highway,  Inc.,  a  Pennsylvania  corporation,  and
Baker/OTS,  Inc.,  a  Delaware  corporation  (individually,   a  "Borrower"  and
collectively,  jointly and severally the "Borrowers"),  and Mellon Bank, N.A., a
national banking association (the "Bank") ("First Amendment").

                                   WITNESSETH:

      WHEREAS,  the  Borrowers  and the Bank  entered  into  that  certain  Loan
Agreement,  dated as of June 12, 1997,  by and among the  Borrowers and the Bank
(as amended from time to time, the  "Agreement")  pursuant to which the Bank has
extended  to the  Borrowers a revolving  credit  loan  facility in the  original
principal  amount  not  to  exceed   Twenty-Five   Million  and  00/100  Dollars
($25,000,000.00); and

      WHEREAS, the Borrowers desire to extend the Expiry Date (as defined in the
Agreement)  for a period of one (1) year, and the Bank desires to permit such an
extension pursuant to the terms and conditions set forth herein.

      NOW,  THEREFORE,  in  consideration  of the premises  contained herein and
other  valuable  consideration,  the receipt and  sufficiency of which is hereby
acknowledged, and intending to be legally bound hereby, the parties hereto agree
as follows:

      1. All capitalized terms used herein,  which are defined in the Agreement,
should  have the same  meaning  herein as in the  Agreement  unless the  context
clearly indicates otherwise.

      2. The  definition  of "Expiry  Date" in Section 1.01 of the  Agreement is
hereby deleted in its entirety and in its stead is inserted the following:

      "Expiry  Date" shall mean May 31, 2001 or such  earlier  date on which the
Revolving Credit Facility Commitment shall have been terminated pursuant to this
Agreement.

      3.  The   Borrowers   and  Bank  hereby   reconfirm   and   reaffirm   all
representations and warranties, agreements and covenants made by and pursuant to
the terms and conditions of the Agreement,  except as such  representations  and
warranties,  agreements and covenants may have heretofore been amended, modified
or waived in writing in accordance with the Agreement.

     4.  The  Borrowers  hereby  represent  and  warrant  to Bank  that  (a) the
Borrowers  have the legal power and  authority to execute and deliver this First
Amendment; (b) the officers of each Borrower executing the First Amendment have




been  duly  authorized  to  execute  and  deliver  same and bind the  respective
Borrower with respect to the provisions  hereof;  (c) the execution and delivery
hereof by the Borrowers and the  performance  and observance by the Borrowers of
the provisions  hereof and of the Agreement and all documents  executed or to be
executed  therewith,   do  not  violate  or  conflict  with  the  organizational
agreements  of any  Borrower or any law  applicable  to Borrowers or result in a
breach of any provision of or  constitute a default  under any other  agreement,
instrument or document  binding upon or  enforceable  against any Borrower;  (d)
this First Amendment, the Agreement and the documents executed or to be executed
by the  Borrowers  in  connection  herewith or  therewith  constitute  valid and
binding obligations of the Borrowers in every respect, enforceable in accordance
with their respective terms.

      5. Borrowers represent and warrant that no Event of Default (as defined in
the Agreement) exists under the Agreement, nor will any occur as a result of the
execution and delivery of this First  Amendment or the performance or observance
of any provision hereof.

      6. Each  reference to the  Agreement  that is made in the Agreement or any
other  document  executed  or to  be  executed  in  connection  therewith  shall
hereafter be construed as a reference to the Agreement as amended hereby.

      7.  Except as  amended  hereby,  all of the terms  and  conditions  of the
Agreement shall remain in full force and effect. This First Amendment amends the
Agreement and is not a novation thereof.

      8. This First Amendment may be executed in any number of counterparts  and
by the different parties hereto on separate  counterparts each of which, when so
executed,  shall  be  deemed  an  original,  but  all  such  counterparts  shall
constitute but one and the same instrument.

      IN WITNESS WHEREOF,  and intending to be legally bound hereby, the parties
hereto have caused the First  Amendment to be duly executed as of the date first
above written.

ATTEST:                             Michael Baker Corporation


By: /s/ H. James McKnight           By: /s/ J. Robert White
- -------------------------           -----------------------
Print Name: H. James McKnight       Print Name: J. Robert White
- -----------------------------       ---------------------------
Title: Senior Vice President        Title: Executive Vice President
- ----------------------------        -------------------------------


ATTEST:                             Michael Baker Jr., Inc.


By: /s/ H. James McKnight           By: /s/ J. Robert White
- -------------------------           -----------------------
Print Name: H. James McKnight       Print Name: J. Robert White
- -----------------------------       ---------------------------
Title: Senior Vice President        Title: Executive Vice President
- ----------------------------        -------------------------------







ATTEST:                             Baker Environmental, Inc.


By: /s/ H. James McKnight           By: /s/ J. Robert White
- -------------------------           -----------------------
Print Name: H. James McKnight       Print Name: J. Robert White
- -----------------------------       ---------------------------
Title: Senior Vice President        Title: Executive Vice President
- ----------------------------        -------------------------------


ATTEST:                             Baker/MO Services, Inc.


By: /s/ H. James McKnight           By: /s/ J. Robert White
- -------------------------           -----------------------
Print Name: H. James McKnight       Print Name: J. Robert White
- -----------------------------       ---------------------------
Title: Senior Vice President        Title: Executive Vice President
- ----------------------------        -------------------------------


ATTEST:                             Baker Support Services, Inc.


By: /s/ H. James McKnight           By: /s/ J. Robert White
- -------------------------           -----------------------
Print Name: H. James McKnight       Print Name: J. Robert White
- -----------------------------       ---------------------------
Title: Senior Vice President        Title: Executive Vice President
- ----------------------------        -------------------------------


ATTEST:                             Baker/Mellon Stuart Construction, Inc.


By: /s/ H. James McKnight           By: /s/ J. Robert White
- -------------------------           -----------------------
Print Name: H. James McKnight       Print Name: J. Robert White
- -----------------------------       ---------------------------
Title: Senior Vice President        Title: Executive Vice President
- ----------------------------        -------------------------------


ATTEST:                             Baker Heavy & Highway, Inc.


By: /s/ H. James McKnight           By: /s/ J. Robert White
- -------------------------           -----------------------
Print Name: H. James McKnight       Print Name: J. Robert White
- -----------------------------       ---------------------------
Title: Senior Vice President        Title: Executive Vice President
- ----------------------------        -------------------------------







ATTEST:                             Baker/OTS, Inc.


By: /s/ H. James McKnight           By: /s/ J. Robert White
- -------------------------           -----------------------
Print Name: H. James McKnight       Print Name: J. Robert White
- -----------------------------       ---------------------------
Title: Senior Vice President        Title: Executive Vice President
- ----------------------------        -------------------------------


                                    Mellon Bank, N.A.

                                    By: /s/ Mark Latterner
                                    ----------------------
                                    Title: Vice President
                                    ---------------------