Filed pursuant to Rule 424(b)(3) and (c)
                                Registration Number 333-88532


PROSPECTUS SUPPLEMENT
(to prospectus dated June 6, 2002 and to the prospectus supplements dated
June 11, 2002, June 17, 2002, June 19, 2002, June 24, 2002, June 26, 2002,
July 10, 2002, July 15, 2002, July 17, 2002, August 5, 2002, August 28, 2002,
September 18, 2002, October 21, 2002, October 25, 2002, October 29, 2002,
November 4, 2002, November 12, 2002, November 18, 2002, December 10, 2002,
February 3, 2003, March 12, 2003, April 3, 2003, and May 16, 2003)


                            $201,250,000

                      OHIO CASUALTY CORPORATION

                    5.00% CONVERTIBLE NOTES DUE 2022
                   AND THE COMMON SHARES ISSUABLE UPON
                   CONVERSION OF THE CONVERTIBLE NOTES
                           _______________

        This prospectus supplement supplements our prospectus dated June 6,
2002 and our prospectus supplements dated June 11, 2002, June 17, 2002, June
19, 2002, June 24, 2002, June 26, 2002, July 10, 2002, July 15, 2002, July
17, 2002, August 5, 2002, August 28, 2002, September 18, 2002, October 21,
2002, October 25, 2002, October 29, 2002, November 4, 2002, November 12, 2002,
November 18, 2002, December 10, 2002, February 3, 2003, March 12, 2003, April
3, 2003, and May 16, 2003 relating to the sale by certain of our
securityholders, or by their transferees, pledgees, donees or other successors,
of up to $201,250,000 aggregate principal amount of our 5.00% convertible
notes due 2022 and the common shares issuable upon the conversion of the notes.
You should read this supplement in conjunction with the prospectus and the
previous prospectus supplements.  This supplement is qualified by reference to
the prospectus and the previous prospectus supplements, except to the extent
the information in this supplement supersedes the information contained in the
prospectus or in the previous prospectus supplements.

        Investing in the notes involves risks.  See "Risk Factors" beginning
on page 8 of the prospectus.

        Neither the Securities and Exchange Commission nor any other state
securities commission has approved or disapproved of these securities or
passed upon the accuracy or adequacy of this prospectus.  Any representation
to the contrary is a criminal offense.



                                SELLING SECURITYHOLDERS

        The following table provides information regarding the principal amount
of notes beneficially owned by certain of our selling securityholders, the
percentage of outstanding notes held by these selling securityholders, the
number of our common shares beneficially owned by these selling
securityholders, the number of our common shares each selling securityholder
would beneficially own upon conversion of its entire principal amount of notes
and the percentage of our outstanding common shares held by these selling
securityholders.

        The table below supplements or amends the table of securityholders
contained on pages 37 through 45 of the prospectus and in the previous
prospectus supplements.  Where the name of a selling securityholder identified
in the table below also appears in the table in the prospectus or in the
previous prospectus supplements, the information set forth in the table below
regarding that selling securityholder supersedes the information in the
prospectus or in the previous prospectus supplements.  This information was
furnished to us by the selling securityholders listed below on or before
May 21, 2003.  Because selling securityholders may trade all or some of
the notes listed at any time without notifying us, the table below may not
reflect the exact value of notes held by each selling securityholder on the
date of this supplement.


          The date of this prospectus supplement is May 21, 2003.








                                                                              Number of
                            Principal                                          Common
                             Amount                          Number of         Shares
                            of Notes                          Common       Underlying the      Percentage
    Name of                Beneficially      Percentage       Shares         Notes and          of Common
    Selling                 Owned and         of Notes     Beneficially       Offered            Shares
Securityholder(1)         Offered Hereby    Outstanding      Owned(2)       Hereby(3)(4)     Outstanding(5)
- -----------------         --------------    -----------    ------------     ------------     --------------
                                                                              


James L. Donald               $500,000           *              0              22,105               *




_______________________________
* Less than 1%


(1)	Also includes any sale of the notes and the underlying common share by
pledgees, donees, transferees or other successors in interest that receive
such securities by pledge, gift, distribution or other non-sale related
transfer from the named selling securityholders.

(2)	Excludes common shares issuable upon conversion of the selling
securityholder's notes.

(3)	Assumes conversion of all of the selling securityholder's notes at a
rate of 44.2112 common shares per note and a cash payment in lieu of the
issuance of any fractional share interest.  However, this conversion rate
is subject to adjustment as described in the prospectus under "Description
of the Notes  -- Conversion Rights."  As a result, the number of common
shares issuable upon conversion of the notes may increase or decrease in
the future.

(4)	Reflects rounding down of fractional common shares issuable to each
selling securityholder upon conversion of the notes.  A cash payment will be
made in lieu of the issuance of any fractional share interest.

(5)	Calculated based on Rule 13d-3 of the Securities Exchange Act of 1934
using 60,845,141 common shares outstanding as of May 20, 2003.  In
calculating this amount, we did not treat as outstanding the common shares
issuable upon conversion of the notes.



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