We studied 28 cases of orbital blowout fracture treated in Department of Otorhinolaryngology, Mie University Hospital, from January, 1984 to March, 1989. There were 23 male patients and 5 female patients ranging from 7 to 59 years of age (average, 21.7 years). In the majority of cases was the present injury occurred during fighting. Vertical double vision was in 50%. The degree of double vision was evaluated before and after surgery and classified as severe, moderate, or mild. Double vision was evaluated before surgery, at the time of extubation of the balloon catheter, and about 3 months after surgery. Improvement was better when surgery was performed within two weeks after the injury. These patients also showed better improvement of other injuries postoperatively. Good postoperative improvement was also seen in patients with a negative preoperative forced duction test. Balloon catheter placement in the maxillary sinus for two weeks is considered to be adequate.