Following intravenous administration, vancomycin is poorly metabolized and is mainly excreted unchanged in urine. Total body clearance is thus dependent on the kidney, and is correlated with glomerular filtration rate and creatinine clearance. Accumulation of vancomycin in patients with renal insufficiency may therefore occur, and this may lead to toxic side effects if dosage is not modified according to the degree of renal failure. Furthermore, vancomycin easily diffuses through dialysis membranes. The aim of the present review is to establish guidelines for handling this drug in such patients. We indicate how and when plasma concentrations of vancomycin should be determined in dialysis patients.