Cyclosporin A (CsA) is an effective therapy for severe intraocular inflammation but nephrotoxicity and hypertension are major side effects even in low dose in combination with oral corticosteroids and clinical studies on the long-term effects of low-dose CsA therapy outside the field of organ transplantation are lacking. This multicentre, open, longitudinal study has been established to evaluate the long-term efficacy and side effects of low-dose CsA therapy (initial dose less than or equal to 5 mg/kg/day, with a maximum dose of 7 mg/kg/day, and total treatment duration greater than 3 months) in severe ocular inflammation where conventional therapy had failed to control the disease or caused intolerable side effects. Visual response to treatment, clinical signs and symptoms of side effects, biochemical and haematological parameters have been recorded at 3-monthly intervals since January 1987 and will continue until December 1993. Data for 74 patients (age 35.5 +/- 16.6 years) and 293 follow up visits are presented in this preliminary report. [table: see text] Other side effects include (% of all visits): hypertrichosis (4.2), headache (2.8), cramps (1.8), arthropathy (1.8), paraesthesiae (1.8), abdominal pain (1.5), weakness (1.5), dyspepsia (1.4), nausea (1.4), others (4).