The nephrotoxicity and pharmacokinetics of teicoplanin were studied in an experimental rat model. Nephrotoxicity was assessed by measuring urinary excretion of tubular cells and malate dehydrogenase. The experiments revealed that 1 mg/kg or more of teicoplanin daily resulted in an increase of excretion rates of tubular cells. Similarly to vancomycin, teicoplanin is accumulated in the kidneys. Nephrotoxicity induced by teicoplanin can be reduced by coadministration of fosfomycin and D-glucaro-1.5-lactam, and enhanced by administration of tobramycin. We conclude that renal function should be monitored closely during teicoplanin therapy.