Antibiotics are used in 80% of patients in the ICU, encouraging nosocomial infections with resistant organisms. If the antibiotic susceptibilities of the pathogen are known, a narrow-spectrum antibiotic is preferable to preserve the patient's resistance to colonization. However, treatment is often empirical and broad-spectrum combinations are commonly used. Gram-positive bacteraemia is associated with invasive monitoring or intravascular catheters. If the device cannot be removed easily, the glycopeptides are the only agents likely to be active against most strains of the commonest pathogen, the coagulase-negative staphylococcus. Long-stay patients are susceptible to infection with enterococci and methicillin-resistant Staphylococcus aureus, which are often resistant to all the usual agents other than glycopeptides. Vancomycin is long established, but is nephrotoxic, requires serum monitoring, must be administered as an infusion and can cause red man syndrome. Teicoplanin can be given as a single daily bolus without similar side-effects or monitoring. In deep-seated staphylococcal infection, the usual dose of teicoplanin is adequate if given in combination with other agents, but it may need to be doubled if used as monotherapy. Monitoring of the levels in the serum is helpful to ensure an adequate dose in patients with renal failure or in drug abusers, but is not needed to prevent toxicity.