Unrelated cord blood transplantation (CBT) has now become more common, but as yet there have been only a few reports on its outcome compared with bone marrow transplantation (BMT), especially for adults. We studied the clinical outcomes of 113 adult patients with hematologic malignancies who received unrelated BM transplants (n = 45) or unrelated CB transplants (n = 68). We analyzed the hematopoietic recovery, rates of graft-versus-host disease (GVHD), risks of transplantation-related mortality (TRM) and relapse, and disease-free survival (DFS) using Cox proportional hazards models. The time from donor search to transplantation was significantly shorter among CB transplant recipients (median, 2 months) than BM transplant recipients (median, 11 months; P < .01). Multivariate analysis demonstrated slow neutrophil (P < .01) and platelet (P < .01) recoveries in CBT patients compared with BMT patients. Despite rapid tapering of immunosuppressants after transplantation and infrequent use of steroids to treat severe acute GVHD, there were no GVHD-related deaths among CB transplant recipients compared with 10 deaths of 24 among BM transplant recipients. Unrelated CBT showed better TRM and DFS results compared with BMT (P = .02 and P < .01, respectively), despite the higher human leukocyte antigen mismatching rate and lower number of infused cells. These data strongly suggest that CBT could be safely and effectively used for adult patients with hematologic malignancies.