Surgical site infections are a frequent cause of morbidity following surgical procedures. Gram-positive cocci, particularly staphylococci, cause many of these infections, although gram-negative organisms are also frequently involved. The risk of developing a surgical site infection is associated with a number of factors, including aspects of the operative procedure itself, such as wound classification, and patient-related variables, such as preexisting medical conditions. Both nonpharmacologic measures and antimicrobial prophylaxis for selected procedures are used to prevent development of these infections. Compliance with these generally accepted preventive principles may lead to overall decreases in the incidence of these infections.