PURPOSE: To determine the effect of age on the outcome of autologous bone marrow transplantation (ABMT) and/or peripheral-blood progenitor-cell (PBPC) transplantation. PATIENTS AND METHODS: A retrospective analysis was performed on 500 consecutive patients who ranged in age from 1 to 65 years (median, 40) with non-Hodgkin's lymphoma (NHL), Hodgkin's disease (HD), multiple myeloma (MM), or acute nonlymphoblastic leukemia (AML) who underwent autologous hematopoietic-cell transplant procedures at Stanford University Medical Center. RESULTS: The actuarial 5-year event-free survival (EFS) rate was 44%, the relapse rate 47%, and the regimen-related mortality (RRM) rate 8.6%. Disease status at time of transplantation, categorized as either minimal or advanced disease, was the strongest predictive factor for EFS (relative risk (RR) for advanced-disease group, 1.8; P < .0003) and relapse rate (RR for advanced-disease group, 1.9; P < .0004). Patients with minimal or advanced disease had an EFS rate of 48% and 30% and relapse rates of 43% and 72%, respectively. The EFS rate of patients less than 50 years verus > or = 50 years of age was 46% versus 34% (P = .03). Cox regression analysis showed that age was predictive for EFS (RR for patients 50 to 65 years, 1.4; P = .03). The actuarial RRM rate for these age groups was 7.4% versus 12.7% (P = .07), respectively. Multivariate analysis demonstrated that age (odds ratio [OR] for patients 50 to 65 years, 1.9; P < .05) and period of transplantation (OR for most recent years [1991 to 1995], 0.6; P = .06) were the most predictive factors for RRM. CONCLUSION: Although age greater than 50 years is associated with an inferior outcome following autologous hematopoietic-cell transplantation, it does not appear to be warranted to limit this potentially curative procedure based solely on age. The upper age limit of high-dose therapy with autologous progenitor-cell and/ or bone marrow support remains to be defined.