The pharmacology, pharmacokinetics, clinical efficacy, adverse effects, and dosage and administration of mupirocin are reviewed. Mupirocin is a naturally occurring antibiotic produced by submerged fermentation of Pseudomonas fluorescens. It inhibits bacterial protein synthesis by binding reversibly and specifically to isoleucyl-tRNA synthetase. Organisms resistant to other antimicrobials are not simultaneously resistant to mupirocin. Mupirocin is highly active against Staphylococcus aureus and other staphylococci and streptococci. When mupirocin ointment is applied topically, local concentrations exceed the inhibitory concentrations for staphylococci and remain detectable for up to 72 hours. Placebo-controlled studies demonstrate the ability of mupirocin to eliminate nasal carriage of S. aureus in health care workers. Observational studies suggest that mupirocin is efficacious in treating methicillin-resistant S. aureus (MRSA) outbreaks. Preliminary studies show that mupirocin might have a role in preventing infections in high-risk patients. Although mupirocin seems to be well tolerated, mild to moderate adverse events have been reported, including respiratory problems and effects confined to the nose—erythema, swelling, burning or stinging, pruritus, and dryness. Mupirocin calcium ointment has FDA-approved labeling for the eradication of nasal MRSA colonization in adult patients and health care workers as part of comprehensive infection-control programs to reduce the risk of infection during institutional outbreaks. The recommended dosage is 0.5 g inserted into each nostril twice daily for five days. Intranasal mupirocin ointment appears to be a useful addition to infection-control programs designed to reduce the risk of infection among patients during MRSA outbreaks.