This review summarizes the clinically relevant aspects of nasal carriage of Staphylococcus aureus. The epidemiology, associated risk, and the effects of eradication are discussed. The main conclusions are that nasal carriage of S. aureus is a well-defined risk factor for subsequent infection in nearly all categories of hospitalized patients that have been studied. However, studies that have been performed to evaluate the effect of eradication of carriage using mupirocin nasal ointment have been inconclusive so far in most subgroups. Only in patients on hemodialysis or chronic ambulatory peritoneal dialysis (CAPD) was a significant reduction of the infection rate found. But prolonged treatment in these groups carries a risk for the development of resistance. In surgical patients two randomized studies have found an effect on the surgical site infection rate in carriers that, when those studies are combined, was close to being statistically significant (p = 0.06). In non-surgical patients a significant delay in the onset of infection was found but the overall infection rate was not significantly different. When the results of all well-designed studies that have been performed are combined, a significant reduction of the nosocomial S. aureus infections in carriers is found (approximately 50% lower). Future studies should focus on treating carriers only and consider other treatment regimens.