Exhibit 5.1

                         LETTERHEAD OF WHITE & CASE LLP

July 8, 2002


Aphton Corporation
80 S.W. 8th Street
Miami, Florida  33130

Re:  Aphton Corporation
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Ladies and Gentlemen:

          We have examined the Registration Statement on Form S-3 (the
"Registration Statement") under the Securities Act of 1933, as amended (the
"Securities Act"), in the form in which it is to be filed by Aphton Corporation
(the "Company") with the Securities and Exchange Commission (the "Commission"),
in connection with the sale by the Company of 5,000,000 shares of common stock,
$.001 par value, of the Company (the "Shares"). The Shares are being registered
for offering and sale from time to time pursuant to Rule 415 under the
Securities Act.

          In connection with our opinion expressed below, we have examined
originals or copies certified to our satisfaction of such agreements, documents,
certificates and other statements of government officials and corporate officers
of the Company and such other papers as we have deemed relevant and necessary as
a basis for such opinion. As to certain facts material to our opinion, we have
relied, to the extent that we deem such reliance proper, upon certificates of
public officials and of officers of the Company. In rendering such opinion, we
have assumed the genuineness of all signatures, the authenticity of all
documents submitted to us as originals and the conformity to authentic original
documents of all documents submitted to us as certified, conformed or
photostatic copies.

          When (i) the issuance of the Shares has been duly authorized by
appropriate corporate action and (ii) the certificates for the Shares have been
duly executed by the Company, countersigned by the transfer agent therefor and
duly delivered to the purchasers thereof against payment therefor, the Shares
will be validly issued, fully paid and nonassessable.

          The opinion expressed above is limited to questions arising under the
Federal law of the United States and the General Corporate Law of the State of
Delaware.




          We consent to the filing of this opinion as an exhibit to the
Registration Statement and to the reference to our firm appearing under the
caption "Legal Matters" in the Prospectus forming part of the Registration
Statement. In giving this consent, we do not thereby admit that we are within
the category of persons whose consent is required under Section 7 of the
Securities Act or the rules and regulations of the Commission.

                                                Very truly yours,


                                                /s/ White & Case LLP