Clinical efficacy of Cefmetazole was evaluated at four university hospitals and their related hospitals in Nagoya. For the treatment of urinary tract infections with or without complications, 177 patients were administered Cefmetazole. Of these patients, 69 had chronic complicated urinary tract infection defined in the UTI manual and 20 had simple acute pyelonephritis. The other urological infections for which Cefmetazole was administered included prostatitis, epididymitis, urosepsis and wound infections. Fifty four patients were given Cefmetazole intravenously after urological operation to prevent wound and urinary tract infections. The overall clinical efficacy of Cefmetazole for UTI was 76.8%; 84.4% for group 1, 85.7% for group 3, 75% for group 4, 44.4% for group 5 and 66.6% for group 6. In acute pyelonephritis due to E. coli, Klebsiella, Serratia, S. aureus, alpha-Streptococcus and S. epidermidis all patients were cured by Cefmetazole administration. Clinical efficacy of Cefmetazole was assessed to be excellent in 6 cases of prostatitis and 6 cases of acute epididymitis. E. Coli, Serratia and some organisms disappeared from blood after the administration of Cefmetazole but Pseudomonas persisted even after treatment. Postoperative administration of Cefmetazole was effective for eradication of bacteria from the urine in 26 out of 30 patients and in prevention of infection in 24 cases. After the administration of Cefmetazole skin eruption was observed in one patient and nausea in another. Slight elevation of GOT, GPT and total bilirubin was noted in 3 of the 177 patients after medication.