EXHIBIT 5.1

[FOLEY & LARDNER LETTERHEAD]

                                 August 8, 2003

Fiserv, Inc.
255 Fiserv Drive
Brookfield, WI 53045

Ladies and Gentlemen:

                We have acted as counsel for Fiserv, Inc., a Wisconsin
corporation (the "Company"), in connection with the preparation of a
Registration Statement on Form S-4, including the Prospectus constituting a part
thereof (the "Registration Statement"), to be filed with the Securities and
Exchange Commission under the Securities Act of 1933, as amended (the
"Securities Act"), relating to an offer to exchange (the "Exchange Offer") the
Company's new 3% Notes due 2008 (the "New Notes") for an equal principal amount
of the Company's outstanding 3% Notes due 2008 (the "Old Notes").

                The Old Notes were issued, and the New Notes will be issued,
pursuant to an Indenture, dated as of June 27, 2003 (the "Indenture"), between
the Company and BNY Midwest Trust Company, as Trustee (the "Trustee").

                In connection with our opinion, we have examined: (a) the
Registration Statement, including the Prospectus; (b) the Indenture; (c) the
form of the New Notes; and (d) such other proceedings, documents and records as
we have deemed necessary to enable us to render this opinion.

                In our examination of the above referenced documents, we have
assumed the genuineness of all signatures, the authenticity of all documents,
certificates and instruments submitted to us as originals and the conformity
with the originals of all documents submitted to us as copies.

                Based upon the foregoing, assuming that the Indenture has been
duly authorized, executed and delivered by, and represents the valid and binding
obligation of, the Trustee, and when the Registration Statement, including any
amendments thereto, shall have become effective under the Securities Act and the
Indenture shall have been duly qualified under the Trust Indenture Act of 1939,
as amended, and having regard for such legal considerations as we deem relevant,
we are of the opinion that the New Notes, when duly executed and delivered by or
on behalf of the Company in the form contemplated by the Indenture upon the
terms set forth in the Exchange Offer and authenticated by the Trustee, will be
legally issued and valid and binding obligations of the Company enforceable in
accordance with their terms except as enforcement thereof may be limited by
bankruptcy, insolvency, fraudulent transfer, reorganization, moratorium or other
comparable laws affecting the enforcement of creditors' rights generally or the
application of equitable principles (regardless of whether such enforceability
is considered in a proceeding in equity or at law).


[FOLEY & LARDNER LETTERHEAD]

                We are qualified to practice law in the State of Wisconsin and
we do not purport to be experts on the law other than that of the State of
Wisconsin and the Federal laws of the United States of America. We express no
opinion and make no representations with respect to the laws of any other
jurisdiction.

                We hereby consent to the reference to our firm under the caption
"Legal Matters" in the Prospectus which is filed as part of the Registration
Statement, and to the filing of this opinion as an exhibit to such Registration
Statement. In giving this consent, we do not admit that we are "experts" within
the meaning of Section 11 of the Securities Act or within the category of
persons whose consent is required by Section 7 of the Securities Act.

                                         Very truly yours,

                                         /s/ FOLEY & LARDNER

                                         FOLEY & LARDNER