Antibiotic prophylaxis reduces the incidence of infections after some types of surgical interventions; in Obstetrics it can prevent infections in high risk situations. Infections can occur in particular situations, even in cesarean sections (CS) at low risk. The incidence of puerperal endometritis is variable in literature, while the incidence of pelvic or surgical wound infections is 3.8% in elective CS with respect to 7.5% in emergency CS. This study verifies the efficacy of the sulbactam-ampicillin association (Unasyn, Pfizer) in the prophylaxis of all cesarean sections, complicated or not. Unasyn was administrated one hour prior to CS and 8 and 16 hours after CS in 162 patients. Therapy was continued in 8 cases because of high risk for infection. The evaluation of the efficacy of the drug was based on clinical criteria. There were no complications or fever recorded and no toxic or allergic reactions occurred. Antibiotic prophylaxis is recommended for all patients undergoing CS.