Although the acute nephrotoxicity of cisplatin has been well documented, long-term follow-up studies are scanty. We have evaluated the renal function in 35 patients who have had completed therapy with cisplatin at least 3 months before the study. All patients had normal serum creatinine levels before chemotherapy. Evaluation of renal function included: serum creatinine, glomerular filtration rate (inulin clearance), effective renal plasma flow (p-aminohippurate clearance), urinary beta 2-microglobulin and N-acetyl-beta-D-glucosaminidase excretion, and renal tomography. The median cumulated dose of cisplatin was 603 +/- 37 mg/m2. The mean serum creatinine level was 78 +/- 21 and 88 +/- 3 mumol/l before and after chemotherapy, respectively (p < 0.05). Mean glomerular filtration rate (92 +/- 4 ml/min) and effective renal plasma flow (362 +/- 21 ml/min) were significantly lower than in controls (110 +/- 3 and 436 +/- 24 ml/min). The mean enzymuria and the renal size remained within the normal range. In 12 patients who were reevaluated 12 and 24 months later, glomerular filtration rate and effective renal plasma flow remained stable. These results suggest that at usual dosages cisplatin is associated with a nonprogressive loss of renal function which is of a moderate degree.