The effects of a combination of topical corticosteroid and cyclosporin A on corneal graft survival were tested in a model of penetrating keratoplasty in the inbred rat. Topical medications were applied four times daily to the graft for 28 days postgraft. Neither topical steroid (1% prednisolone acetate) nor topical cyclosporin (1% in chremophor EL/ethanol) was able to modify the overall incidence of rejection, though all steroid-containing medications delayed the onset of rejection significantly. The combined formulation of steroid plus cyclosporin A caused a reduction in the incidence of rejection which did not reach statistical significance and which did not eliminate the response in all animals. The chremophor/ethanol vehicle was reasonably well tolerated but did cause some periocular dermatitis.