Abstract Background Tinnitus is a serious late effect of childhood cancer treatment. The aim of this study was to determine the occurrence and risk factors for tinnitus in a national cohort of childhood cancer survivors (CCS). Methods Data were collected within the national Dutch Childhood Oncology Group - Long-Term Effects after Childhood Cancer (DCOG-LATER) cohort by a self-reported health questionnaire among 5327 Dutch CCS treated between 1963 and 2002. Siblings (N = 1663) were invited to complete the same questionnaire. Relevant patient characteristics and treatment factors were obtained from the Dutch LATER database. The occurrence of tinnitus in survivors was compared to siblings. To study the effect of risk factors, multivariate logistic regression models were estimated. Results In total, 2948 CCS and 1055 siblings completed the tinnitus item. Tinnitus was reported in 9.5% of survivors and in 3.7% of siblings (odds ratio [OR] 3.0, 95% confidence interval [CI] 2.9–3.1). Risk factors associated with tinnitus in CCS were total cumulative dose cisplatin ≥400 mg/m2 (OR 2.4, 95% CI 1.4–4.0), age at diagnosis (≥10 years: OR 2.1, 95% CI 1.6–2.8), cranial irradiation/total body irradiation (TBI; OR 1.9, 95% CI 1.5–2.5), and neuro/ear, nose, throat (ENT) surgery (OR 1.8, 95% CI 1.1–2.9). Fifty-one percent of CCS with tinnitus had received treatment with either cisplatin, cranial irradiation/TBI, and/or neuro/ENT surgery. Conclusions Tinnitus in CCS was present nearly 3 times more often than in siblings. Awareness in CCS previously treated with cisplatin, cranial irradiation/TBI, and/or neuro/ENT surgery is warranted. As only half of affected CCS had a history of these treatments, it seems that other factors might be associated with tinnitus occurrence in this population.