Objectives/Hypothesis: Although it is well known that cisplatin is associated with ototoxicity, there is still a lack of knowledge concerning the ototoxicity of cisplatin, especially in Japanese head and neck cancer patients. The objectives of this study were to determine the incidence rate of cisplatin ototoxicity and to determine the threshold dose causing ototoxicity in the Japanese population. Study Design: Before-and-after study in a tertiary referral hospital. Methods: The distortion product otoacoustic emission (DPOAE) was measured 1 week after each administration of cisplatin in 44 Japanese head and neck cancer patients treated at Kyoto University Hospital. We determined the incidence and threshold dose of cisplatin ototoxicity according to DPOAE data. Results: The incidence of ototoxicity detected by DPOAE was 77.3%. The average DPOAE value was significantly lower in patients who received more than 200 mg/m ² cisplatin than the baseline DPOAE value. The threshold dose for cisplatin ototoxicity was lower in Japanese patients than in European patients. Conclusions: Our data suggest that Japanese patients are more susceptible to cisplatin-induced ototoxicity. This is presumably caused by a genetic difference. © 2012 The American Laryngological, Rhinological, and Otological Society, Inc