F.N.B. (FNB) S-4/A Registration of securities issued in business combination transactions (amended)

Exhibit 23.3

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We consent to the incorporation by reference in this Amendment No. 1 to Registration Statement No. 333-120438 of F.N.B. Corporation on Form S-4 of our report dated January 31, 2003 appearing in the Annual Report on Form 10-K of NSD Bancorp, Inc. for the year ended December 31, 2002 and the reference to us under the heading “Experts” in the proxy statement/prospectus, which is part of this Registration Statement.

/s/ DELOITTE & TOUCHE LLP

Pittsburgh, Pennsylvania
January 13, 2005