By the early 1980s, perioperative prophylaxis in vaginal hysterectomy had been shown consistently to be of such value in reducing postoperative infection that some authors maintained that further placebo-controlled studies were no longer ethical. The benefit of prophylaxis in abdominal hysterectomy was less uniformly demonstrated, in studies which were prospective, placebo-controlled, double-blind and randomised. Prophylaxis may significantly reduce the incidence of febrile morbidity and/or wound/pelvic infection, the duration of hospital stay, or the total usage of antibiotics. It is therefore generally agreed that each centre should itself scientifically evaluate the efficacy of prophylaxis before a decision on its routine use in abdominal hysterectomy is made. In comparative studies, agents which were active against both anaerobic and aerobic organisms were more efficacious than those active against anaerobes only. Antibiotics with similar spectra of activity showed similar efficacy in both types of hysterectomy. Multiple- and single-dose regimens of the same antibiotics also showed equal efficacy. The new cephalosporins with a longer half-life were attractive theoretically as agents in single-dose regimens; ceftriaxone, however, has been shown to have an adverse effect on the normal gut flora. With the increased numbers of induced abortions carried out in the UK and other parts of the world in recent years, the need to reduce postabortal infection is generally appreciated. The results of early studies using tetracyclines as the prophylactic agents were difficult to evaluate because of the incomplete follow-up and different definitions of pelvic infections. No benefit was demonstrated in 2 studies using a single preoperative dose of tinidazole, whereas oral metronidazole in 3 doses and penicillin/pivampicillin for 4 days were shown to be efficacious in reducing postabortal infection. In a recent study with doxycycline, significant benefit was shown in patients with negative preoperative screening for gonococcal and chlamydial infection. These genital infections, together with a history of previous pelvic inflammatory disease (PID)/gonorrhoea, nulliparity with multiple partners, young age of the patient and gestational age have been described as significant risk factors. Some researchers hold the view that selective prophylaxis based on these risk factors should be practised instead of mass prophylaxis. All agree that an antibiotic regimen that is both efficacious and well tolerated has yet to be found.