In 19 evaluable cancer patients treated with cis-diamminedichloroplatinum (cis-DDP) Platidiam-Lachema containing chemotherapy the ototoxicity was assessed. There was an increase of hearing threshold of air-conduction in frequency of 6000 and 8000 Hz as compared with pretreatment audiograms in four patients (21%). In one case only the hearing loss was reversible. The usual hearing loss was of 10--15 dB and maximal of 20 dB. In those four patients with ototoxicity the decrease of creatinine clearence under 60 ml/min occurred at the same time. It is suggested that the altered renal function could be a cause of cis-DDP level rise in body liquids and in this way a cause of further more severe side effects. Neither subjective hearing loss nor tinnitus nor otalgia was found. The cis-DDP caused high frequency hearing loss but has not affected the correct speech percept. To avoid serious cis-DDP ototoxicity it is necessary to monitor renal functions and audiograms carefully and to administer cis-DDP slowly in chloride-containing vehicles after sufficient prehydratation.