A prospective, randomised study was carried out on 110 patients to find out the effect of giving Cefotetan prophylactically as against no treatment in the prevention of infections after cesarean sections. The cases were selected before or at the beginning of a trial of labour in 72 cases and after a failure of trial of labour in 38 cases. A single dose of 2 gr of Cefotetan was given during the operation, after the cord had been clamped. It caused a significant drop in infection and in particular the number of cases of endometritis and urinary tract infections, which were twice as common in the non-treated as compared with the treated group.