Six male patients with severe psoriatic arthritis (PA) unresponsive to various topical and systemic therapies have been treated with oral cyclosporin A (CyA; Sandimmun) solution at daily doses ranging usually from 1.5 to 5.0 mg/kg. In 1 case the dose had to be increased to 7 mg/kg/day. At initiation of CyA therapy skin involvement was between 40 and 90% of total body surface. Initiation of CyA therapy resulted in marked improvement of skin lesions within 2-7 weeks accompanied by impressive relief from arthralgias and improvement of joint function. The requirement for nonsteroidal anti-inflammatory drugs was markedly reduced in all cases. All patients in whom CyA therapy was continued remained clinically stable for several months (follow-up period 2-7 months). Although mild to moderate relapses occurred, rebound phenomena were not observed after discontinuation of treatment. Side effects which comprised serum creatinine increases in 3 out of 6 cases were reversed by adjustment of CyA dosage.