We studied the clinical outcomes of 171 adults with hematologic malignancies who received unrelated cord blood transplantation (CBT) as a primary unrelated stem-cell source (n=100), or bone marrow transplant (BMT) or peripheral blood stem-cell transplant (PBSCT) from related donors (n=71, 55 BMT and 16 PBSCT). All patients received myeloablative regimens including 12 Gy total body irradiation. We analyzed the hematologic recovery, and risks of graft-versus-host disease (GVHD), transplantation-related mortality (TRM) and relapse, and disease-free survival (DFS) using Cox proportional hazards models. Significant delays in engraftment occurred after cord blood transplantation; however, overall engraftment rates were almost the same for both grafts. The cumulative incidences of grades III to IV acute and extensive-type chronic GVHDs among CBT recipients were significantly lower than those among BMT/PBSCT recipients. Multivariate analysis demonstrated no apparent differences in TRM (9% in CBT and 13% in BMT/PBSCT recipients), relapse (17% in CBT and 26% in BMT/PBSCT recipients), and DFS (70% in CBT and 60% in BMT/PBSCT recipients) between both groups. These data suggest that unrelated cord blood could be as safe and effective a stem-cell source as related bone marrow or mobilized peripheral blood for adult patients when it is used as a primary unrelated stem-cell source.