We have carried out a controlled, prospective, randomized study with the aim of evaluating the efficacy of a short-term antibiotic prophylaxis on patients undergoing simple total hysterectomy. 750 patients entered the trial, starting in September 1977, 260 underwent vaginal hysterectomy, 490 abdominal hysterectomy. The patients were subdivided randomly into four groups, which were homogeneous in number, age, weight, associated disease, indication for surgery and hormonal status: control group, without treatment; prophylaxis with Cefazolin; prophylaxis with Thiamphenicol; prophylaxis with Cefazolin plus Thiamphenicol. Each antibiotic was administered parenterally, at the dose of 1 g, 1 hour before surgery, and 5 and 12 hours later. Postoperative infectious morbidity was evaluated according to febrile morbidity, the need for antibiotic therapy during the postoperative period and the length of postoperative hospitalization. The incidence and severity of febrile morbidity was significantly reduced in the three groups of patients who received prophylaxis. The use of antibiotics in the postoperative period resulted significantly reduced and the period of hospitalization was shorter for the groups with prophylaxis than for the control group.