A retrospective review of 288 penetrating keratoplasties (PKP) for herpes simplex keratitis demonstrated a 60.4% survival rate of clear grafts at 3 years. A highly significant difference in corneal graft survival in severely vascularized corneas (57.1% at 3 years) versus non- or slightly vascularized corneas (82.8% at 3 years) was observed (P = 0.009). Prospectively HLA-A and -B matched grafts in vascularized corneas revealed a significantly improved graft survival when compared to unmatched grafts (P = 0.035). Corneal graft survival in eyes grafted 'à chaud' was not significantly below the graft survival of vascularized corneas with a clinically non-active herpetic corneal disease. Recurrence of herpes simplex in the graft was observed in an earlier postoperative period in HLA-A and -B matched grafts (P = 0.0004).