We assessed late mortality in 1479 individuals who had survived 2 or more years after allogeneic hematopoietic cell transplantation (HCT). Median age at HCT was 25.9 years and median length of follow-up was 9.5 years. The conditional survival probability at 15 years from HCT was 80.2% (SE = 1.9%) for those who were disease-free at entry into the cohort, and the relative mortality was 9.9 (95% confidence interval, 8.7-11.2). Relative mortality decreased with time from HCT, but remained significantly elevated at 15 years after HCT (standardized mortality ratio = 2.2). Relapse of primary disease (29%) and chronic graft-versus-host disease (cGVHD: 22%) were the leading causes of premature death. Nonrelapse-related mortality was increased among patients older than 18 years at HCT (18-45 years: relative risk [RR] = 1.7; 46+ years: RR = 3.7) and among those with cGVHD (RR = 2.7), and was lower among patients who received methotrexate for GVHD prophylaxis (RR = 0.5). HCT survivors were more likely to report difficulty in holding jobs (odds ratio [OR] = 13.9), and in obtaining health (OR = 7.1) or life (OR = 9.9) insurance compared with siblings. This study demonstrates that mortality rates remain twice as high as that of the general population among 15-year survivors of HCT, and that the survivors face challenges affecting their health and well-being.