The efficacy and safety of cyclosporin for patients with rheumatoid arthritis (RA) were assessed in a six month double blind, placebo controlled, multicentre study. The initial dosage of the drug was 10 mg/kg daily for two months. There were many discontinuations in both the cyclosporin group (eight out of 17) and the placebo group (six out of 19). Of the patients who completed the six months of therapy, those who had received cyclosporin showed a significant improvement in the number of swollen joints, the Ritchie articular index, and pain at active movement and at rest, compared not only with their condition at the start of the study, but also with the end results of the placebo group. Major adverse reactions to the drug were gastrointestinal disturbances and nephrotoxicity, which were probably due to the relatively high dosages of cyclosporin given in combination with non-steroidal anti-inflammatory drugs.