Forty nine keratoplasties were performed in 18 eyes of 17 patients with severe corneal destructive disease.One eye became phthisical and 5 others lost useful visual acuity but retained a satisfactory cosmetic result. No eyes were enucleated. Recurrence of the host disease in the graft was the largest cause of visual failure. Primary allograft rejection was rare in spite of the large size of the grafts and their proximity to the limbus and new vessels.For these grafts to succeed it is essential to bring the underlying systemic disease under control by intensive systemic immunosuppressive therapy before, during and for many months after surgery. It was found that those with Mooren's ulcer had the worst prognosis for the retention of vision.