Purpose Survivors of childhood cancer may experience financial burden as a result of health care costs, particularly because these patients often require long-term medical care. We sought to evaluate the prevalence of financial burden and identify associations between a higher percentage of income spent on out-of-pocket medical costs (≥ 10% of annual income) and issues related to financial burden (jeopardizing care or changing lifestyle) among survivors of childhood cancer and a sibling comparison group. Methods Between May 2011 and April 2012, we surveyed an age-stratified, random sample of survivors of childhood cancer and a sibling comparison group who were enrolled in the Childhood Cancer Survivor Study. Participants reported their household income, out-of-pocket medical costs, and issues related to financial burden (questions were adapted from national surveys on financial burden). Logistic regression identified associations between participant characteristics, a higher percentage of income spent on out-of-pocket medical costs, and financial burden, adjusting for potential confounders. Results Among 580 survivors of childhood cancer and 173 siblings, survivors of childhood cancer were more likely to have out-of-pocket medical costs ≥ 10% of annual income (10.0% v 2.9%; P < .001). Characteristics of the survivors of childhood cancer that were associated with a higher percentage of income spent on out-of-pocket costs included hospitalization in the past year (odds ratio [OR], 2.3; 95% CI, 1.1 to 4.9) and household income < $50,000 (OR, 5.5; 95% CI, 2.4 to 12.8). Among survivors of childhood cancer, a higher percentage of income spent on out-of-pocket medical costs was significantly associated with problems paying medical bills (OR, 8.9; 95% CI, 4.4 to 18.0); deferring care for a medical problem (OR, 3.0; 95% CI, 1.6 to 5.9); skipping a test, treatment, or follow-up (OR, 2.1; 95% CI, 1.1 to 4.0); and thoughts of filing for bankruptcy (OR, 6.6; 95% CI, 3.0 to 14.3). Conclusion Survivors of childhood cancer are more likely to report spending a higher percentage of their income on out-of-pocket medical costs, which may influence their health-seeking behavior and potentially affect health outcomes. Our findings highlight the need to address financial burden in this population with long-term health care needs.