Although nephrotoxicity has frequently limited conventional treatment with cisplatin to doses of 100-120 mg/m2 per cycle, vigorous chloruresis can permit the administration of high-dose cisplatin (200 mg/m2 per cycle) with minimal nephrotoxicity. Systemic toxicities are worsened, but therapeutic response seems to be enhanced. The pharmacokinetics of cisplatin in plasma and urine were examined to assess the causes of these effects. Plasma disappearance of ultrafiltrable platinum was well-described by a single exponential for each patient. The mean t1/2 was 50% longer for patients receiving high-dose cisplatin than for patients receiving conventional doses. The total systemic exposure was three times greater in the high-dose group, which tends to explain the systemic toxicity and improved tumor efficacy, but not the lack of nephrotoxicity. It is suggested that the kidneys of patients in the high-dose group were relatively protected by dilution of active Pt species in the urine in the tubule lumen as well as by high chloride ion concentrations in the urine.