Forearm has a unique function of supination and pronation and for the performance of such movements, normal relationship between radius and ulna is indispensable. In ulnar shaft fracture, injuries are resulted mostly from .the external forces such as direct blows or indirect forces in some cases. There are many procedures for treatment of isolated ulnar fracture, but there are still controversies concerning the best management of these fractures. The authors treated fifteen cases surgically of ulnar shaft fracture from January 1982 to December 1986 in the Deparment of Orthopedic Surgery, National-Police Hospital. The results were as follows: 1. The most common age group was twenties with twelve cases(80.0%). 2. The most common cause of injuries were direct blow(80.0%). 3, Location of fracture were middle one third with nine cases(60.6%), while proximal one third accounts for four cases (26.7%) and distal ond third for two cases(13.3%). 4. Transverse fracture were the most common type (53.3%). 5. Displacement of fractures, out of fifteen cases, were witnessed in twelve cases (80.0%) and angulation were in eleven cases(73.3%). 6. In all cases we used operative method and had good functional results.