Fifty-five patients with psoriatic arthritis were treated with a low dose of cyclosporin A (CyA) (mean dose 2.7 mg/kg per day) for a period of 6 months to investigate the efficacy of CyA on disease parameters. Significant improvement in the joint complaints and inflammation parameters was observed including a decrease in the number of painful (-46%) and swollen (-45%) joints, tenderness (Ritchie Index: -50%) and degree of swelling (-46%), patient's assessment of pain (-35%), the duration of morning joint stiffness (-37%), as well as a decrease in C-reactive protein (-52%). A 50% reduction of joint complaints required a total of 24 weeks, whereas a 50% reduction of skin involvement was achieved after 5-6 weeks of treatment. Four patients left the study due to adverse events: creatinine level increase in two patients, hypertension in one patient and gastroenteritis in the fourth patient. Joint scintigraphy in 18 patients indicated an improvement or stable condition in 61% of cases after a mean follow-up of approximately 8 months. The results of this prospective study show that low-dose CyA effectively improves not only skin lesions, but also joint complaints in psoriatic arthritis.