HSCT is being increasingly offered as a curative option for children with hematologic malignancies. Although survival has improved, the long-term morbidity ascribed to the HSCT procedure is not known. We compared the risk of chronic health conditions and adverse health among children with cancer treated with HSCT with survivors treated conventionally, as well as with sibling controls. HSCT survivors were drawn from BMTSS (N = 145), whereas conventionally treated survivors (N = 7207) and siblings (N = 4020) were drawn from CCSS. Self-reported chronic conditions were graded with CTCAEv3.0. Fifty-nine percent of HSCT survivors reported ≥ 2 conditions, and 25.5% reported severe/life-threatening conditions. HSCT survivors were more likely than sibling controls to have severe/life-threatening (relative risk [RR] = 8.1, P < .01) and 2 or more (RR = 5.7, P < .01) conditions, as well as functional impairment (RR = 7.7, P < .01) and activity limitation (RR = 6.3, P < .01). More importantly, compared with CCSS survivors, BMTSS survivors demonstrated significantly elevated risks (severe/life-threatening conditions: RR = 3.9, P < .01; multiple conditions: RR = 2.6, P < .01; functional impairment: RR = 3.5, P < .01; activity limitation: RR = 5.8, P < .01). Unrelated donor HSCT recipients were at greatest risk. Childhood HSCT survivors carry a significantly greater burden of morbidity not only compared with noncancer populations but also compared with conventionally treated cancer patients, providing evidence for close monitoring of this high-risk population. © 2011 by The American Society of Hematology.