Exhibit 23 CONSENT OF INDEPENDENT ACCOUNTANTS We consent to the incorporation by reference in the Registration Statements (Form S-8 Nos. 333-69895 and 333-87413) pertaining to the Employees' Savings Plan of Ohio Casualty Insurance Company of our report dated June 13, 2003, with respect to the financial statements and schedules of the Ohio Casualty Insurance Company Employees' Savings Plan included in this Annual Report (Form 11-K) for the year ended December 31, 2002. /s/Ernst and Young LLP Cincinnati, Ohio June 23, 2003