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                                                                   EXHIBIT 10.27

                        AMENDMENT TO LOAN AGREEMENT AND
                  INTEREST RATE AND FOREIGN CURRENCY AGREEMENT
                AND MODIFICATION OF NOTES EVIDENCING TERM LOANS

          THIS AMENDMENT TO LOAN AGREEMENT AND INTEREST RATE AND FOREIGN
CURRENCY AGREEMENT AND MODIFICATION OF NOTES EVIDENCING TERM LOANS
("Amendment") dated as of December 23, 1997 (the "Amendment Effective Date") is
made and entered into by and among SMITH INTERNATIONAL, INC. (the "Borrower"),
a Delaware corporation, the banking institutions (each, together with its
successors and assigns, a "Bank" and collectively, the "Banks") from time to
time a party to the Loan Agreement (as hereinafter defined), as amended by this
Amendment, ABN AMRO BANK N.V., HOUSTON AGENCY and DEN NORSKE BANK AS, as
Co-Agents (in such capacity, together with their successors in such capacity,
collectively called the "Co- Agents") and TEXAS COMMERCE BANK NATIONAL
ASSOCIATION ("TCB"), a national banking association, as agent for the Banks (in
such capacity, together with its successors in such capacity, the "Agent").


 RECITALS:

         WHEREAS, the Borrower, the Banks, the Co-Agents, and the Agent are
parties to a Loan Agreement dated as of April 4, 1996, as amended by instrument
dated April 8, 1997 (the "Loan Agreement"); and

         WHEREAS, certain provisions regarding interest rates and foreign
currency matters in respect of the obligations of the Borrower under the Loan
Agreement have been gathered in that certain Interest Rate and Foreign Currency
Agreement (the "Interest Rate and Foreign Currency Agreement") attached as
Schedule 1 to the Loan Agreement; and


         WHEREAS, the Borrower, the Banks, the Co-Agents, and the Agent have
agreed, on the terms and conditions herein set forth, that the Loan Agreement
and Interest Rate and Foreign Currency Agreement be amended in certain
respects;

         NOW, THEREFORE, IT IS AGREED:

         Section 1.  Definitions.  Terms used herein which are defined in the
Loan Agreement shall have the same meanings when used herein unless otherwise
provided herein.

         Section 2.  Amendments to the Loan Agreement. On and after the
Amendment Effective Date, the Loan Agreement shall be amended as follows:

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      (a)       The definition of "Commitment Fee Percentage" contained in
Section 1. 1 of the Loan Agreement is hereby amended to read in its entirety as
follows:

                Commitment Fee Percentage  shall mean, on any day, the
      applicable per annum percentage set forth at the appropriate intersection
      in the table shown below, based on the. Rating (as defined in the Interest
      Rate and Foreign Currency Agreement) as of the close of business on the 
      preceding Business Day:

<TABLE>
<CAPTION>
                                                            Commitment Fee
                 Rating                                     Percentage
                 ------                                     ----------
                 <S>                                        <C>
                 A-/A3 or higher                            0.090%

                 BBB+/Baa1                                  0.100%

                 BBB/Baa2                                   0.150%

                 BBB-/Baa3                                  0.175%

                 BB+/Bal or lower                           0.200%
</TABLE>


      (b)       The definition of "Maturity Date" contained in Section 1. 1
of the Loan Agreement is hereby amended to read in its entirety as follows:

                Maturity Date shall mean the maturity of the Notes evidencing
      the Revolving Loans, December 31, 2002, as the same may hereafter be
      accelerated pursuant to the provisions of any of the Loan Documents.

      (c)       A new definition of "Net Worth" is hereby added to Section 1.1
of the Loan Agreement, such new definition to read in its entirety as follows:

                Net Worth shall mean all items classified as assets (valued at
      cost less normal depreciation) in the financial statements of the
      applicable Person delivered in accordance with this Agreement, less all
      items classified as liabilities in the financial statements of such
      Person delivered in accordance with this Agreement (including contingent
      and indirect liabilities to the extent included on the balance sheet of
      the applicable Person), all determined in accordance with GAAP. The term
      "liabilities" shall include, without limitation, (1) Indebtedness secured
      by Liens on Property of the Person with respect to which Net Worth is
      being computed, whether or not such Person is liable for the payment
      thereof; (2) deferred liabilities, and (3) Capital Lease Obligations. The
      term "Net Worth" shall include any direct or indirect minority interest
      in M-I.


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        (d)       A new definition of "Term Loan Maturity Date" is hereby
added to Section 1.1 of the Loan Agreement, such new definition to read in its
entirety as follows:

                  Term Loan Maturity Date shall mean the maturity of the Notes
        evidencing the Term Loans, March 31, 2001, as the same may hereafter
        be accelerated pursuant to the provisions of any of the Loan Documents.

        (e)       Section 3.2(d) of the Loan Agreement is hereby amended to
read in its entirety as follows:

                  (d)    Term Loan Amortization. The principal of each Note
          evidencing Term Loans shall be due and payable in semiannual
          installments due on each six month anniversary of the making of the
          Term Loans equal to the applicable Term Loan Lender's pro rata share
          of the Term Loans times 32,000,000 Krone. On the Term Loan Maturity
          Date, the entire unpaid principal balance of each Note evidencing
          Term Loans and all accrued and unpaid interest on the unpaid
          principal balance of each such Note shall be finally due and payable.

        (f)       Section 7.3(a) of the Loan Agreement is hereby amended to
read in its entirety as follows:

                  (a)    Debt to Total Capitalization Ratio - a Debt to Total
        Capitalization Ratio of not greater than 45%.

        (g)       Section 7.3(c) of the Loan Agreement is hereby amended to read
in its entirety as follows:

                  (c)    Net Worth - Net Worth of not less than (1) for the
        period commencing on December ____, 1997 through and including December
        31, 1997, $490,000,000 and (2) for each fiscal quarter thereafter, the
        minimum Net Worth required during the immediately preceding fiscal
        quarter plus 50% of the Net Income (if positive) of the Borrower for
        the immediately preceding fiscal quarter plus 100% of any increase in
        Net Worth during such fiscal quarter resulting from any merger, sale or
        issuance of equity.

        (h)       The reference in Section 11.5 of the Loan Agreement to the
phrase "Maturity Date" is hereby amended to read "Maturity Date or Term Loan
Maturity Date".

        Section 3.       Amendments to the Interest Rate and Foreign Currency
Agreement. On and after the Amendment Effective Date, the Interest Rate and
Foreign Currency Agreement shall be amended as follows:

        (a)       The definition of "Eurocurrency Margin Percentage" contained
in Section 1 of the Interest Rate and Foreign Currency Agreement is hereby
amended to read in its entirety as follows:

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         Eurocurrency Margin Percentage means, on any day and with respect to
any Loan, the applicable per annum percentage set forth at the appropriate
intersection in the table shown below, based on the Rating as of the close of
business on the preceding Business Day:

<TABLE>
<CAPTION>
                                             Eurocurrency Margin              Eurocurrency Margin
                                             Percentage for Euro-             Percentage for Euro-
               Rating                        dollar Rate Borrowings           krone Rate Borrowings
               ------                        ----------------------           ---------------------
          <S>                                        <C>                              <C>
          A-/A3 or higher                            0.250%                           0.375%
          BBB+/Baal                                  0.300%                           0.425%
          BBB/Baa2                                   0.350%                           0.475%
          BBB-/Baa3                                  0.400%                           0.525%
          BB+/Bal or lower                           0.625%                           0.750%
</TABLE>

     (b)         Each reference in the Interest Rate and Foreign Currency
  Agreement to the phrase "Maturity Date" is hereby amended to read "Maturity
  Date or Term Loan Maturity Date, as the case may be".

     (c)         A new definition of "Rating" is hereby added to Section 1 of
  the Interest Rate and Foreign Currency Agreement, such new definition to read
  in its entirety as follows:

                 Rating shall mean the senior debt rating for Borrower publicly
     announced by Standard & Poor's Ratings Group or Moody's Investors Service,
     Inc. In the event the ratings are not equivalent, the higher rating shall
     be treated as the "Rating"' hereunder; provided, that if such ratings 
     differ by more than one (1) level, the Rating shall be the average, 
     rounded upwards, of the two ratings.

     Section 4.       Modification of the Notes Evidencing Term Loans. On
and after the Amendment Effective Date, each reference in the Notes evidencing
the Term Loans to the phrase "Maturity Date" is hereby amended to read "Term
Loan Maturity Date".

     Section 5.       Limitations.  The amendments set forth herein are
limited precisely as written and shall not be deemed to (a) be a consent to, or
waiver or modification of, any other term or condition of the Loan Agreement or
any of the other Loan Documents, or (b) except as expressly set forth herein,
prejudice any right or rights which the Banks may now have or may have in the
future under or in connection with the Loan Agreement, the Loan Documents or
any of the other documents referred to therein. Except as expressly modified
hereby or by express written amendments thereof, the terms and provisions of
the Loan Agreement, the Notes, and any other Loan Documents or any other
documents or instruments executed in connection with any of the foregoing are
and shall remain in full force and effect. In the event of a conflict between
this Amendment and any of the foregoing documents, the terms of this Amendment
shall be controlling.

     Section 6.       Payment of Expenses.  The Borrower agrees, whether or
not the transactions hereby contemplated shall be consummated, to reimburse and
save the Co-Agents, the Agent and the Bank(s) harmless from and against
liability for the payment of all reasonable


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substantiated out-of-pocket costs and expenses arising in connection with the
preparation, execution, delivery and enforcement of, or the preservation of any
rights under this Amendment, including, without limitation, the reasonable fees
and expenses of any local or other counsel for the Agent, and all stamp taxes
(including interest and penalties, if any), recording taxes and fees, filing
taxes and fees, and other similar charges which may be payable in respect of,
or in respect of any modification of, the Loan Agreement and the other Loan
Documents. The provisions of this Section shall survive the termination of the
Loan Agreement and the repayment of the Loans.

     Section 7.       Governing Law. This Amendment and the rights and
obligations of the parties hereunder and under the Loan Agreement shall be
construed in accordance with and be governed by the laws of the State of Texas
and the United States of America.

     Section 8.       Descriptive Headings, etc. The descriptive headings
of the several Sections of this Amendment are inserted for convenience only and
shall not be deemed to affect the meaning or construction of any of the
provisions hereof.

     Section 9.       Entire Agreement.  This Amendment and the documents
referred to herein represent the entire understanding of the parties hereto
regarding the subject matter hereof and supersede all prior and contemporaneous
oral and written agreements of the parties hereto with respect to the subject
matter hereof, including, without limitation, any commitment letters regarding
the transactions contemplated by this Amendment.

     Section 10.      Counterparts.  This Amendment may be executed in any
number of counterparts and by different parties on separate counterparts and
all of such counterparts shall together constitute one and the same instrument.
Complete sets of counterparts shall be lodged with the Borrower and the Agent.

     Section 11.      Amended Definitions.  As used in the Loan Agreement
(including all Exhibits thereto) and all other instruments and documents
executed in connection therewith, on and subsequent to the Amendment Effective
Date the term (i) "Agreement" shall mean the Loan Agreement as amended by this
Amendment, and (ii) references to any and all other Loan Documents shall mean
such documents as amended as contemplated hereby.

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             NOTICE PURSUANT TO TEX BUS. & COMM. CODE SECTION 26.02

     THIS AMENDMENT AND ALL OTHER LOAN DOCUMENTS EXECUTED BY ANY OF THE PARTIES
BEFORE OR SUBSTANTIALLY CONTEMPORANEOUSLY WITH THE EXECUTION HEREOF TOGETHER
CONSTITUTE A WRITTEN LOAN AGREEMENT AND REPRESENT THE FINAL AGREEMENT BETWEEN
THE PARTIES AND MAY NOT BE CONTRADICTED BY EVIDENCE OF PRIOR, CONTEMPORANEOUS
OR SUBSEQUENT ORAL AGREEMENTS OF THE PARTIES.  THERE ARE NO UNWRITTEN ORAL
AGREEMENTS BETWEEN THE PARTIES.

     IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be
duly executed and delivered by their respective duly authorized offices as of
the date first above written.


                                             SMITH INTERNATIONAL, INC.


                                             By:
                                                -------------------------------

                                             Name:
                                                  -----------------------------

                                             Title:         
                                                   ----------------------------






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