To ascertain the efficacy of systemic cyclosporin therapy in the management of scleritis we performed an open, uncontrolled study of the use of this drug in severe refractory disease. Five of seven patients whose disease had previously been poorly controlled with a combination of corticosteroids and immunosuppressive drugs responded to cyclosporin therapy (10 mg/kg/day). Systemic side effects occurred in all but one patient, with tremor, hirsutism, hypertension, and raised serum creatinine being common. Recurrence of disease activity on decreasing the dosage of cyclosporin was frequent. The results indicate that cyclosporin is a useful additional drug in the treatment of severe scleritis.