Platinum concentrations in plasma were measured by atomic absorption spectrometry during and after a 15 min intravenous infusion of cis-dichlorodiamineplatium (II) (cis-platinum) at a dose of 100 mg/m2. Plasma concentrations of platinum declined biexponentially (t 1/2 alpha = 21.3 min, t 1/2 beta = 6.2 days). A small peak was noticed at 3.5 hrs after the end of the infusion, indicating a renewed influx of platinum in the plasma compartment. This phenomenon is strongly suggestive for the presence of an enterohepatic circulation.