This study identified two risk factors associated with severe hearing loss (HL) in children with medulloblastoma treated with PSPT, which are patient age <7 years at radiotherapy and a mean cochlear dose (Dmc) ≥36 Gy. Among the 79 patients included in this study, 27 patients (34%) had grade 3-4 HL. The predicted 3-year incidence of grade 3-4 HL was 40.0% and 66.7% for children with Dmc ≥36 Gy and age at radiotherapy ≥7 and <7 years (p=0.042). It was 8.9% and 15.6% for children with Dmc <36 Gy and age at radiotherapy ≥7 and <7 years (p=0.78).