The pharmacokinetics of platinum in cancer patients were examined following an intravenous infusion of cis-diammine(glycolato) platinum, 254-S. The plasma concentrations of total platinum, which decreased biexponentially after the infusion, were proportional to the dose over the range of 10 to 120 mg/m2, suggesting linearity of the pharmacokinetics. The plasma concentrations of ultrafilterable platinum were similar to those of total platinum and there was little difference in the pharmacokinetic parameters between total platinum and ultrafilterable platinum. These findings show that almost all of the platinum derivative is unbound, which is thought to be the active form, in plasma after administration of 254-S. Platinum was eliminated from blood faster when given as 254-S rather than as cisplatin because of the low protein binding. The urinary recovery within 24 hours was about half of the dose, suggesting that platinum given as 254-S was distributed to various tissues and organs in an active form.