A prospective study was carried out over 12 months involving twenty-eight patients with psoriatic arthritis. Almost all patients improved dramatically with regard to both pain and function. Clinical assessment including evaluation of number of swollen joints, joint tenderness score, and morning stiffness was performed by external observer without any knowledge of previous evaluation data. These data together with patients' assessment of pain and assessment of general condition, consumption of analgetics, and sedimentation rate improved significantly after three and six or twelve months. Apart from transient increases in serum transaminases no other abnormalities developed during the study.