[Stationery of Keating, Muething & Klekamp, P.L.L.]


GARY P. KREIDER
DIRECT DIAL:  (513) 579-6411
FACSIMILE:  (513) 579-6956
E-MAIL:  GKREIDER@KMKLAW.COM

                                June 30, 2000


Hemagen Diagnostics, Inc.
34-40 Bear Hill Road
Waltham, Massachusetts   02154

Gentlemen:

     We serve as your general counsel and are familiar with your  Certificate of
Incorporation, By-laws and corporate proceedings. On this basis, we have made an
examination as to:

     1. The organization of Hemagen Diagnostics, Inc.;

     2. The  legal  sufficiency  of all  corporate  proceedings  of  Hemagen  in
connection with the authorization and issuance of all presently  outstanding and
issued common stock of Hemagen; and

     3. The legal  sufficiency of all corporate  proceedings taken in connection
with the  authorization and issuance of 7,054,703 shares of Hemagen common stock
and 2,601,800  warrants to purchase common stock (the "Warrants") to be included
in a  Registration  Statement  on Form S-3 to be filed with the  Securities  and
Exchange Commission.

     Based upon such examination, we are of the opinion that:


     1. Hemagen is a duly organized and validly existing  corporation  under the
laws of the State of Delaware;

     2. After conversion of Hemagen's 8% Senior Subordinated Secured Convertible
Notes and exercise of the Warrants  (each in  accordance  with their  respective
terms) the aforesaid  7,054,703  shares of Hemagen  common stock will be validly
authorized,  legally  issued,  fully  paid and  nonassessable  shares of Hemagen
common stock free of any preemptive rights.








     3. The aforesaid 2,601,800 Warrants are validly authorized,  legally issued
and fully paid.

     We hereby consent to be named in the aforesaid  Registration  Statement and
the prospectus part thereof as the attorneys who will pass upon legal matters in
connection with the issuance of the aforesaid  common stock and to the filing of
this opinion as an exhibit to the Registration Statement and furthermore consent
to references made to this firm in the Registration Statement.

                                  Yours truly,

                                  KEATING, MUETHING & KLEKAMP, P.L.L.


                                  BY:/s/ Gary P. Kreider
                                     ---------------------------------
                                         Gary P. Kreider