Antibiotics, especially cephems, have been improved remarkably in the last 20 years. In order to evaluate the improvement of antibiotics used for the prophylaxis of infections after radical hysterectomy, two groups of patients (group A, 1978-1979, n = 54; group B, 1985-1987, n = 55) were examined in regard to bacteriological and clinical effects. In spite of the improvement of antibiotics, the positive rate of bacteriological analysis had increased from 44.4 to 76.4%. Obvious decrease of gram-negative bacilli and increase of gram-positive cocci (GPC), e.g. Enterococcus, were observed. In contrast, fever index and febrile morbidity of group B decreased significantly more than those of group A. These results indicate that the improvement of antibiotics has brought more effective prophylaxis in the postoperative infection in spite of the high positive rate of GPC.