The present study reports corneal allogeneic transplantation in a rat model. The technique used was full-thickness penetrating keratoplasty. Fisher rats were used as donors and Lewis rats were used as recipients. The rate of acute rejection obtained in this model with this combination of strains was 100%. It therefore seems to be a very useful model for the study of rejection and for the study of new immunosuppressive treatment. The effect of systemic cyclosporine (CsA) treatment on graft rejection was assessed using this model. Rejection was prevented by CsA as long as treatment was given but occurred in most grafts within 10 days of treatment cessation. Thus, tolerance could not be induced with CsA which, however, significantly reduced graft neovascularization.