A total of 20 hospitalized patients underwent orthopedic surgery in the Tokyo Metropolitan Police Hospital during the period from December 1981 to March 1982. These patients were treated with cefoxitin, mainly, for the prevention of postoperative infections. The following clinical findings were obtained. 1. Out of the 20 patients, 14 were judged 'good' and 6 'fair'. 2. No side effects were reported by the patients or were evident in the clinical data. 3. These clinical results indicated that cefoxitin is a very effective antibiotic for the prevention of postoperative infections in orthopedic surgery.