The short-term efficacy of cyclosporine in the treatment of six patients with moderately severe to severe psoriatic arthritis was evaluated in an open study. Patients received oral cyclosporine (6 mg/kg/d) for eight weeks. In all patients, significant improvement of psoriasis was noted within two to four weeks. At the end of therapy, rheumatologic assessment revealed the following trends in disease activity: a decrease in the number of tender joints, joint tenderness index, duration of morning stiffness, and an increase in grip strength. There was a decrease in the number of swollen joints, joint swelling index, and the time taken to walk 50 ft. Overall disease activity significantly improved as assessed independently by the patient and physician. For psoriasis and psoriatic arthritis, disease activity worsened toward baseline within four weeks of discontinuation of therapy. Short-term, low-dose cyclosporine therapy may be effective in treating psoriasis and psoriatic arthritis.