EXHIBIT 5.1

July 15, 2002

Board of Directors
ChemFirst Inc.
700 North Street
Jackson, Mississippi 39202-3095

RE:   Opinion Letter

Gentlemen:

I currently serve as General Counsel for ChemFirst Inc. (the "Company"), a
Mississippi corporation. In connection with the preparation of the Company's
Form S-8 Registration Statement (the "Registration Statement") covering 600,000
shares of its Common Stock ($1.00 par value) and 600,000 phantom share units
valued relative to the Company's Common Stock (the "Share Units") which may be
offered under the ChemFirst Inc. 1998 Long-Term Incentive Plan, as amended May
23, 2000 and May 21, 2002 (the "Plan"), I have examined and am familiar with the
Company's Amended and Restated Articles of Incorporation, its Bylaws, the Plan,
the Registration Statement, applicable resolutions passed by the Company's Board
of Directors, and with such other documents and questions of law as I have
deemed necessary or appropriate for the purposes of this opinion.

I am of the opinion, based upon such examinations, that the 600,000 shares of
the Company's Common Stock ($1.00 par value) and the 600,000 Share Units covered
by the Registration Statement have been duly authorized by all necessary
corporate action of the Company and, when issued in accordance with the terms
and conditions of the Plan and the instruments governing their issuance, the
shares of Common Stock will be legally and validly issued, fully paid and
non-assessable and the Share Units will be legally and validly issued and
represent the binding obligation of the Company to make payment to the holders
thereof in accordance with the terms and conditions of the Plan.

This opinion is limited solely to the laws of the State of Mississippi and the
laws of the United States, and I express no opinion herein concerning the laws
of any other jurisdiction. I hereby consent to the filing of this opinion as an
exhibit to the Registration Statement and to the reference to me and to my being
named under the caption "Interests of Named Experts and Counsel" in the
Registration Statement.

Sincerely yours,

CHEMFIRST INC.

/s/ J. Steve Chustz
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J. Steve Chustz
General Counsel

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