Distal radioulnar is a part which has a rotational movement through the function of distal radioulnar joint and extensor carpi ulnaris. The injury mechanism in this area is usually a trauma largely due to traffic accidents. In general these injuries to the distal radioulnar joint are treated by a closed reduction. However, the isolated distal ulnar fracture without radial fracture, which is often called the night stick fracture, is difficult to treat by a closed reduction and a cast immobilization alone, especially if there is a displacement or fracture segment impinging soft tissue or severe comminution. Nonunion has been the frequent outcome with this method of treatment and limitation of rotation of forearm and distal radioulnar joint have occurred due to long period of immobilization or malunion. Thus, a different treatment modality such as open reduction and internal fixation and early active joint motion has arisen as a better treatment modality. In this study, 8 cases of isolated distal ulnar fracture without radial fracture have recieved the operation and the early active joint movement, if a displacement was present either at the time of injury or after the initial closed reduction. As a result, this method has enabled the patients to reduce the rate of complication of nonunion and to recover limitation of joint motion in a shorter time period.