Tumor necrosis factor is a cytokine with nonspecific antitumor activity, which, in addition to cytostatic and cytolytic effects on tumor cells in vivo, shows activity in the metabolism of many different cells. After reports of increased TNF production with lipopolysacchrides, studies in rat models have revealed that peritoneal macrophages of rats treated with cisplatin released TNF and IL-1. Starting with the assumption that the release of TNF was dependent on the dose and time of cisplatin administration, we designed a study to investigate the activation kinetics of this cytokine by using serum samples obtained at 0, 8, 24 hours after, and on the 3rd and 7th day of cisplatin containing chemotherapy regimens. The baseline values were below 20 pg/ml in all patients, and the levels did not display any significant change during treatment.