Kienbock's disease is a rare disease that is suspected to be caused by the circulatory impairment or/and trauma to the lunate. The various modes of etiology, progression and the treatment have been suggested without any definite ones. The authors report 13 cases of the Kienbock's disease and the results are as follows:1. The male(10 of 13 patients) and the dominate hand(10 of 13 hands) were the more prevalent. 2. Eight cases had a definite history of trauma and the 5 of them were injured by the hyperextension of the wrist. 3. Eight cases were stage III B according to the Lichtman's classification. 4. Nine cases(69%) showed ulna minus variant, which was thought to have certain significant relation with the cause of this disease.