Three patients with advanced refractory malignancies were treated with whole-body hyperthermia (WBH: 42-42.3 degrees C) for 2 h during which time they also received an infusion of 60 or 80 mg/m2 of cis-diamminedichloroplatinum II (DDP). Each patient developed an elevated serum creatinine (2.7-13.6 mg/dl), with maximum creatinine occurring between days 7 and 12 after treatment. WBH did not alter plasma or urinary pharmacokinetics of total or ultrafilterable platinum compared with pharmacokinetic data of the same or other patients given DDP euthermically. Although the mechanism of the renal damage is unclear, it appears that WBH can potentiate the nephrotoxic actions of DDP and that further study of this combination is not warranted.