Concentrations of platin were determined with the method of atomic absorption spectroscopy in plasma and urine from the 1st until 28th day after cis-DDP (3 mg/kg) infusion for 1, 8, and 24 h. Maximum of plasma concentration was measured always at the end of the application time. Minimal concentration was 1.9 micrograms/ml, maximal concentration 5.8 micrograms/ml. Platin could be detected until the 21st respectively 28th day between 0.01 and 0.9 micrograms/ml. The duration of cis-DDP infusions was without influence on the mean excretion of platin. Between 24 and 25% of the infused platin was excreted after 24 h, between 4.8 and 7% after further 24 h, between 1 and 2% between the 3rd and 21st day, and less than 1% thereafter. Difference in pattern of toxicity could not be clearly detected.