Curative but potentially mutagenic cancer therapy might lead to untoward disorders and increased hospitalization among the offspring of childhood cancer survivors. Hospitalizations in childhood were evaluated in a population-based cohort of 1,920 offspring of 3,963 childhood cancer survivors, 6,394 offspring of 5,657 siblings and 9,594 population-based comparisons. The Danish Cancer Registry, Central Population Register and National Hospital Register were used to identify study subjects and hospitalizations. The probability for children in the offspring cohorts of being hospitalized before a given age was estimated using the Kaplan–Meier method. Hospitalization rate ratios (HRRs) were calculated using a Cox proportional hazards model with population comparisons as referent. Little differences in hospitalization histories were seen among offspring in the 3 cohorts. HRRs of overall hospitalization was 1.05 (95% CI, 0.98–1.12) for offspring of survivors and 1.01 (95% CI, 0.97–1.05) for offspring of siblings, neither of which was significantly different from that of population comparisons. No significant associations were seen for most of the main diagnostic groups of diseases including infections and perinatal disorders. A 6-fold excess risk of hospitalization for malignant tumors in survivors' offspring, however, could largely be explained by hereditary cancer syndromes, and part of the 2-fold excess hospitalization for benign tumors might similarly be explained by an underlying genetic susceptibility or by increased surveillance of children born to survivors. Assuming that hospitalization is an indicator of multifactorial genetic disease, the findings provide further reassurance that cancer therapies do not confer a high risk of such conditions in offspring born after treatments.