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                                                                       EXHIBIT 5



                               September 22, 2000



Cardinal Health, Inc.
7000 Cardinal Place
Dublin, OH 43017

Ladies and Gentlemen:

I am the Assistant General Counsel, Practice Group Head, Securities and
Corporate Governance Group, at Cardinal Health, Inc., an Ohio corporation
("Cardinal" or the "Company"), and have acted as such in connection with the
Registration Statement on Form S-3 (the "Registration Statement") being filed by
the Company with the Securities and Exchange Commission (the "Commission") under
the Securities Act of 1933, as amended (the "Securities Act"), relating to the
registration of $1,000,000,000 of: (i) Cardinal common shares, without par value
("Common Shares") and (ii) unsecured debt securities of Cardinal (the "Debt
Securities" and, collectively with the Common Shares, the "Offered Securities").
The Debt Securities are to be issued under an Indenture between the Company and
Bank One, N.A. (formerly known as Bank One, Columbus, N.A.), as trustee (the
"Indenture Trustee"), and one or more supplemental indentures thereto
(collectively, the "Indenture"). Capitalized terms not otherwise defined herein
have the respective meanings specified in the Registration Statement.

In rendering this opinion, I have examined and relied upon a copy of the
Registration Statement. I have also examined, or have arranged for the
examination by an attorney or attorneys under my general supervision, originals,
or copies of originals certified or otherwise certified to my or their
satisfaction, of such agreements, documents, certificates and other statements
of governmental officials and other instruments, and have examined such
questions of law and have satisfied myself as to such matters of fact, as I have
considered relevant and necessary as a basis for this opinion. I have assumed
the authenticity of all documents submitted to me as originals, the genuineness
of all signatures, the legal capacity of all natural persons and the conformity
with the original documents of any copies thereof submitted to me for
examination.

Based on the foregoing, it is my opinion that:

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 1. The Debt Securities will be legally issued and binding obligations of the
   Company (except to the extent enforceability may be limited by applicable
   bankruptcy, insolvency, reorganization, moratorium, fraudulent transfer or
   other similar laws affecting the enforcement of creditors' rights generally
   and by the effect of general principles of equity, regardless of whether
   enforceability is considered in a proceeding in equity or at law) when: (i)
   the Registration Statement, as finally amended (including any necessary
   post-effective amendments), shall have become effective under the Securities
   Act; (ii) the Indenture shall have been qualified under the Trust Indenture
   Act of 1939, as amended, and duly executed and delivered by the Company and
   the Indenture Trustee; (iii) an appropriate prospectus supplement with
   respect to the particular Debt Securities then being sold by the Company
   shall have been filed with the Commission pursuant to Rule 424 under the
   Securities Act; (iv) the Company's Board of Directors or duly authorized
   committee thereof shall have duly adopted final resolutions authorizing the
   issuance and sale of the Debt Securities, as contemplated by the Registration
   Statement and Indenture; (v) the supplemental indenture under which the
   particular Debt Securities are to be issued shall have been duly executed as
   provided in the Indenture and such resolutions; and (vi) the Debt Securities
   shall have been duly executed, authenticated and delivered to the purchasers
   thereof against payment of the agreed consideration therefor.

2. The Common Shares will be legally issued, fully paid and non-assessable when:
   (i) the Registration Statement, as finally amended (including any necessary
   post-effective amendments), shall have become effective under the Securities
   Act; (ii) the Company's Board of Directors or a duly authorized committee
   thereof shall have duly adopted final resolutions authorizing the issuance
   and sale of the Common Shares as contemplated by the Registration Statement
   and prospectus supplement relating thereto and the Common Shares are issued
   in a manner consistent therewith; and (iii) the certificates representing the
   Common Shares shall have been duly executed, countersigned and registered and
   duly delivered to the purchasers thereof against payment of the agreed
   consideration therefor.

This opinion is expressed as of the date hereof. For purposes of this opinion,
I have assumed that there will be no changes in the laws currently applicable to
the Company and that such laws will be the only laws applicable to the Company.
I disclaim any undertaking to advise you of any subsequent changes in the facts
stated or assumed herein or of any subsequent changes in applicable laws.

I do not find it necessary for the purposes of this opinion to cover, and
accordingly I express no opinion as to, the application of the securities or
blue sky laws of the various states to the sale of the Offered Securities.

I am a member of the bar of the State of Ohio and I express no opinion as to
the laws of any jurisdiction other than the State of Ohio.
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I hereby consent to the filing of this opinion as an exhibit to the Company's
Registration Statement on Form S-3 relating to the Offered Securities. I also
consent to the reference to me under the caption "Legal Opinions" in the
Registration Statement. In giving this consent, I do not hereby admit that I am
included in 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/ Amy B. Haynes
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                                        Amy B. Haynes
                                        Assistant General Counsel