Cisplatin is an effective chemotherapeutic agent against pediatric cancers; however, ototoxicity is a concern. This study describes the frequency, severity, and clinical course of hearing loss in Japanese pediatric patients treated with cisplatin-based multimodal therapy. A total of 55 children who received cisplatin-based therapy from 1983 to 2012 underwent audiologic evaluations. Data were analyzed to determine the onset, time-to-progression, and severity of hearing loss. Thirty-five patients, 12 of 16 older patients (4 y or older), and 23 of 39 younger patients (under 4 y), including 7 of 8 patients treated with cisplatin, carboplatin, and radiotherapy, developed hearing loss. Ten of 18 patients who received a cumulative cisplatin dose of <360 mg/m2 developed hearing loss at a minimum dose of 200 mg/m2. Median time to onset after the last cisplatin dose was 71 days; 6 patients developed hearing loss after ≥2 years. Four patients required hearing aids, 6 patients developed progressive hearing loss with time, and 4 patients exhibited persistent hearing failure at low frequencies. Risk factors for acquired hearing loss and its severity may be associated with a combination of factors such as cisplatin and carboplatin therapy, radiotherapy, age at diagnosis, and genetic background. Our results suggested that all pediatric patients treated with cisplatin would have their hearing evaluated regularly, irrespective of the cumulative cisplatin dose as a suggestion, and that further prospective studies regarding ototoxicity including genetic polymorphisms analysis were required.