Long-term survival is now an expected outcome after hematopoietic cell transplantation (HCT). However, the burden of morbidity long-term after HCT remains unknown. We examined the magnitude of risk of chronic health conditions reported by 1022 HCT survivors and their siblings (n = 309). A severity score (grades 1 [mild] through 4 [life-threatening]) was assigned to each health condition using the Common Terminology Criteria for Adverse Events, Version 3. Sixty-six percent of the HCT survivors reported at least one chronic condition; 18% reported severe/life-threatening conditions; comparable values in siblings were 39% and 8%, respectively (P < .001). The cumulative incidence of a chronic health condition among HCT survivors was 59% (95% confidence interval [CI], 56%-62%) at 10 years after HCT; for severe/life-threatening conditions or death from chronic health conditions, the 10-year cumulative incidence approached 35% (95% CI, 32%-39%). HCT survivors were twice as likely as siblings to develop a chronic condition (95% CI, 1.6-2.1), and 3.5 times to develop severe/life-threatening conditions (95% CI, 2.3-5.4). HCT survivors with chronic graft-versus-host disease were 4.7 times as likely to develop severe/life-threatening conditions (95% CI, 3.0-7.2). The burden of longterm morbidity borne by HCT survivors is substantial, and long-term follow-up of patients who received transplantation is recommended.