Clinical features and roentgenographic findings of 37 patients (65 hands) with congenital ankylosis of the digital joints, including symphalangism and other types of congenital ankylosis of the joints, were analyzed. Congenital ankylosis of the digital joints was divided into four types according to the clinical features as follows; Type A (typical symphalangism), 13 cases, Type B (symphalangism without associated anomalies), 6 cases, Type C (symphalangism associated with hypoplasia of the affected digit), 10 cases and Type D (symphalangism as a part of syndrome), 8 cases. Roentgenographic findings of the affected joints were divided into 4 types, such as normal type (Type I), narrow type (Type 2), flat type (Type 3) and bony ankylosis (Type 4). There seems to be 4 types of joint development in congenital ankylosis of the digital joints. In Types 1 and 2, the joint space of the affected joint and the secondary ossification center looks normal. The joint seems to develop normally in Type 1, but the condyle of the affected joint becomes flat in Type 2. In Type 3, the joint space is narrow in infancy, the secondary ossification center fuses with the proximally located phalanx and finally the affected joint develops bony ankylosis. In Type 4, there is osseous fusion of the affected joint at birth. Key words: hand, joint, symphalangism, tarsal coalition, carpal coalition