The combination of bleomycin, etoposide and cis-platinum (BEP) is an effective treatment for germ cell tumours. To help define the role of recently developed non-nephrotoxic analogues of cis-platinum we have analysed the long term renal damage caused by this agent. We report on 22 patients studied 8-60 months following BEP chemotherapy. In the 17 cases with no pre-chemotherapy renal impairment there was a fall in mean glomerular filtration rate from 132 ml/min (95% confidence interval 123, 141) pre-chemotherapy to 103 ml/min (95% confidence interval 94, 113) on late follow up. The overall pattern is one of initial fall of glomerular filtration rate during chemotherapy, and no consistent evidence of late recovery or further deterioration; considerable individual variation is observed.