Psoriatic arthritis is defined as an association of psoriasis with an arthropathy characterized mainly by osteolytic changes in the X-ray. To assess its frequency among Japanese psoriatic patients and to characterize their signs and symptoms, we examined 51 patients (37 males, 14 females) for arthropathy of the fingers. Seven patients (5 males, 2 females) had abnormal X-ray findings of the hands. They were compared with psoriatic patients without arthritis epidemiologically, clinically, and hematologically. Metacarpal indices were also measured and compared with the results from rheumatic arthritis patients and controls.