Investigations were done in 10- and 55-day-old Wistar rats. Glutathione (GSH) level in kidney was decreased by 8 mmol buthionine sulfoximine (BSO)I100 g BW. There was no effect on the renal function and nephrotoxicity of cisplatin (0.6 mg CPI100 g BW) in adult rats. In young rats BSO treatment was followed by neph-rotoxic effects. Pt concentration remained unaffected by BSO in young and adult rats. GSH concentration in kidney was increased by 100 mg acetyl-cysteine (ac-cys)/100 g BW. CP nephrotoxicity was lower in young as well as in adult ac-cys-treated rats. Pt levels in renal tissue were significantly decreased in rats from both age groups. From our results we conclude that the beneficial effect of high GSH concentration in renal tissue on CP nephrotoxicity is the result of decreased Pt concentration in kidney.