Perioperative infections are important causes of morbidity and mortality in surgical patients. The major sites of these infections are the wound, lungs and urinary tract. A great deal of information is now known concerning the epidemiology of these infections. Infection control practices have been designed to interrupt the transmission of microorganisms, enhance host defenses and prevent infection. In some situations, such as with non-clean surgical procedures, the use of prophylactic antibiotics has further reduced the rate of nosocomial infections. However, prophylactic antibiotics can also predispose to infections with antibiotic-resistant bacteria; they are not routinely recommended for the prevention of postoperative pneumonia or urinary tract infection. New approaches for infection control are now being developed to lower perioperative infection rates to an irreducible minimum.