BACKGROUND: People who receive treatment for cancer during childhood often experience subsequent complications of therapy, known as late effects, which can lead to an increased risk of death. PROCEDURE: Using deidentified population-based data from the Australian Childhood Cancer Registry for children aged 0-14 diagnosed with cancer during the period 1983-2011 and who survived for a minimum of 5 years, we examined disease-related deaths (other than cancer recurrence or second primary cancers) that occurred up to 31 December 2016. Risk of death relative to the general population was approximated using standardised mortality ratios (SMRs). Treatment received was stratified according to the intensity of treatment rating, version 3 (ITR-3). RESULTS: During the study period, 82 noncancer disease-related deaths were recorded among 13 432 childhood cancer survivors, four times higher than expected (SMR = 4.43, 95% CI = 3.57-5.50). A clear link to treatment intensity was observed, with the relative risk of noncancer disease-related mortality being twice as high for children who underwent 'most intensive' treatment (SMR = 5.94, 95% CI = 3.69-9.55) compared to the 'least intensive' treatment group (SMR = 2.98, 95% CI = 1.42-6.24; Ptrend  = .01). Thirty-year cumulative mortality from noncancer disease-related deaths was estimated at 1.4% (95% CI = 1.1-1.9) after adjusting for competing causes of death such as cancer, accidents, or injuries. CONCLUSIONS: Although childhood cancer survivors are at increased relative risk of death from noncancer diseases, particularly those who undergo more intensive treatment, the cumulative mortality within 30 years of diagnosis remains small. Knowledge of late effects can guide surveillance of survivors and treatment modification, without wanting to compromise the high rates of survival.