Exhibit 5.1

                      [Letterhead of Halliburton Company]

                                                                   July 17, 2001

Halliburton Company
3600 Lincoln Plaza
500 N. Akard St.
Dallas, TX 75201-3391

Dear Ladies and Gentlemen:

   I have acted as counsel for Halliburton Company in connection with
Halliburton's registration statement on Form S-4 (the "Registration Statement")
relating to the offering, sale and delivery of shares (the "Shares") of
Halliburton's common stock, par value $2.50 per share, pursuant to the proposed
merger of Halliburton MS, Inc., a Delaware corporation and a wholly owned
subsidiary of Dresser Industries, Inc., a Delaware corporation with and into
Magic Earth, Inc., a Delaware corporation.

   In furnishing this opinion, I, or attorneys under my supervision for this
purpose, have examined Halliburton's Restated Certificate of Incorporation and
the By-laws, each as amended to the date hereof, the records of certain
corporate proceedings that occurred prior to the date hereof, including
resolutions adopted by Halliburton's Board of Directors, the Registration
Statement and such other documents as I have deemed necessary and appropriate
to provide a basis for the opinions set forth below. In this examination, I
have assumed the genuineness of all signatures, the authenticity of all
documents submitted to me as original documents and conformity to original
documents of all documents submitted to me as certified or photostatic copies.

   On the basis of the foregoing, I am of the opinion that:

     1. Halliburton has been duly incorporated and is validly existing as a
  corporation under the laws of the State of Delaware.

     2. The issuance of the Shares has been duly authorized by all necessary
  corporate action on the part of Halliburton.

     3. The Shares have been validly authorized for issuance and, upon
  issuance as described in the Registration Statement, will be validly
  issued, fully paid and nonassessable.

   This opinion is limited to the laws of the United States and the State of
Texas and the General Corporation Law of the State of Delaware, all as in
effect as of the date hereof.

   I hereby consent to the filing of this letter as an exhibit to the
Registration Statement.

                                          Very truly yours,

                                          /s/ John M. Allen
                                          _________________________
                                          John M. Allen
                                          Assistant General Counsel
                                          and Assistant Secretary