Fourty-nine patients with blowout fracture of orbital floor or medial orbital wall treated at our Department from October, 1981 to April, 1993 were studied statistically in order to investigate the relation between the time or methods of operation and postoperative results. Orbital floor fractures were frequently occurred in teens of age. The grade of double vision was severer in cases of pure type blowout fracture than impure type fracture. In 32 cases of orbital floor fracture, either eyelid approach, transantral approach, or the two combined approach was used, and the defects of orbital floor were reconstructed with autogenous bone grafts from the anterior wall of maxillary sinus, orbital floor, or iliac bone in 18 cases. Eyelid approach was superior to transantral approach in the postoperative results on double vision. The prognosis of patients reconstructed with anterior wall of maxillary sinus was worst in cases of orbital floor reconstruction. Postoperative improvement of double vision was better in patients having surgery within two weeks after the injury than in those having surgery more than two weeks later.