Abstract: Clinical and roentgenologic analysis of 40 cases of psoriatic arthritis showed that skin lesions of psoriasis developed prior to the joint symptoms in 29 eases, after in 5 and simultaneously in 6. The chief joints affected were finger, toe, hand and foot joints. 27 cases had varying degrees of nail involvement. The roentgenologic characteristics were the involvement of terminal interphalangeal joints of the hands and feet with narrowing of joint space, osseous erosion and bony proliferation. The rheumatoid factor rests were negative in 94.7%. The differential diagnosis between psoriatic arthritis and rheumatoid arthritis was discussed.