BACKGROUND. The authors investigated the risk of delayed chronic kidney disease (CKD) in 1190 adult hematopoietic cell transplantation (HCT) survivors who underwent HCT for hematologic malignancies or aplastic anemia between 1976 and 1997 and survived for at least 1 year. METHODS. CKD was defined as a sustained elevation of serum creatinine that indicated a glomerular filtration rate of <60 mL per minute per 1.73 m 2 for ≥3 months. The median age at HCT was 35 years (range, 18.1-68.6 years), and the median length of follow-up was 7.1 years after HCT (range, 1-24.3 years). RESULTS. Sixty patients with CKD were identified, resulting in a cumulative incidence of 4.4% at 5 years (autologous HCT, 3.8%; matched-sibling HCT, 4.5%; unrelated donor HCT, 10%; P = .09 compared with autologous HCT). Older age at HCT (relative risk [RR] per 5-year increment, 1.33; 95% confidence interval [CI], 1.2-1.5), exposure to cyclosporine without tacrolimus (RR, 1.90; 95% CI, 1.1-3.4) or with tacrolimus (RR, 4.59; 95% CI, 1.8-11.5), and a primary diagnosis of multiple myeloma (RR, 2.51; 95% CI, 1.1-5.6) were associated with an increased risk of delayed CKD. CONCLUSIONS. In this study, the authors identified a subpopulation of patients who underwent HCT and remained at increased risk for CKD. The current findings set the stage for appropriate long-term follow-up of vulnerable patients. © 2008 American Cancer Society.