Cis-platinum induced hearing loss has been reported to be high tone hearing loss over 2 to 8 kHz. This study examined serial audiometry data from 75 patients, treated with Cis-platinum for evaluation of the ototoxic effects of this drug. The results were as follows. 1) Patients showing hearing loss above 15 dB comparing to pretreatment were 37 cases (49.3%), and most of them had hearing loss below 25 dB. 2) Most cases showed hearing loss over 4 kHz to 8 kHz range, and the highest incidence of the maximum hearing loss was 8 kHz in frequency. 3) The degree of hearing loss had no relation to the dosage of Cis-platinum, and the average dosage of the drug inducing hearing loss over 15 dB was 178 mg. 4) All cases showing hearing loss had manifested within 4 days. 5) No typical peripheral vertigenous symptoms were found, 6) In conclusion, Cis-platinum induced hearing loss is mild in degree in high frequency over 2 KHz, early manifested within 4 days, and not related with the dosage or vestibulotoxicity.