Infections are still the most frequent postoperative complications and one of the limiting factors of successful gynaecological surgery. In recent years information on successful anti-microbial chemoprophylaxis is increasing and is associated with reduced postoperative inflammations, febrile morbidity and early complications. Views differ above all as regards indications for the use of antibiotic prophylaxis and the selection of a suitable antibiotic. Data in the literature differ also as regards achieved results. The submitted work had the objective to test on a representative group the success and rationality of medicamentous prophylaxis in gynaecological surgery and to contribute to a clearer view on controversial points. 203 women admitted to the Second Gynaecological and Obstetric Department of the First Medical Faculty Charles University and General Faculty Hospital Prague for elective abdominal or vaginal hysterectomy on account of a benign indication were divided into three groups which did not differ from the demographic or medical aspect. In group A (53 women) for prophylaxis two doses of Augmentin were used (combination of amoxycillin with clavulanic acid) i.v., patients in group M (50 women) had three doses of Mandol (Cefamandol) i.m., and in control group K (100 patients) no antibiotics were administered prophylactically. The authors investigated the postoperative course and evaluated some parameters in relation to possible postoperative infectious complications. The results proved unequivocally that prophylaxis with Augmentin reduces significantly the postoperative infectious morbidity (11.5%), febrile morbidity (5.6%) and the incidence of early infectious complications (3.8%) after abdominal or vaginal hysterectomy, as compared with the control group (35%, 31% and 11% resp.). Prophylaxis with Cefamandol reduced only in few parameters postoperative complications, but in general did not lead to a significant improvement of the postoperative course nor to a reduction of postoperative inflammatory complications. Similar results were obtained when only complications after abdominal hysterectomy were evaluated. The results of bacteriological examination confirmed the expected differences in the spectrum of efficacy of the two antibiotics on the most common microbial flora in the given area, i.e. a high sensitivity of Augmention to enterococci and bacterioids and resistance of these bacteria to Mandol. These results can be considered one of the reasons of different results of the two antibiotics. Prophylaxis with amoxycillin/clavulanic acid was found to be safe, very effective and financially feasible prevention of postoperative infectious complications after abdominal and vaginal hysterectomy. It led to a significant increase in the number of cases without any complications, when compared with the control group.