Purpose: To compare hematologic recovery in patients receiving allogeneic blood cell transplantation (BCT) with those receiving allogeneic bone marrow transplantation (BMT). Patients and Methods: One hundred eleven patients with leukemia in the early stages and with HLA-matched sibling donors were randomized in this study. One hundred one underwent transplantation, Standard procedures for collection and transplantation were used. Patients did not receive prophylactic granulocyte colony-stimulating factor after undergoing transplantation. In addition to clinical end points being established, a prospective and comparative economic evaluation of the first 6 months after transplantation was performed. Results: Groups were balanced for patient, donor, and transplant characteristics. Blood cell collection led to the collection of a higher number of CD34(+) and CD3(+) cells than did bone marrow collection (p < 10(-6)) without reported side effects for the donor. Patients in the BCT group reached platelet counts of 25 and 50 x 10(9) platelets/L 8 and it days earlier than did the BMT group (P < 10(-4) and P < 10(-5)), respectively. This resulted in fewer platelet transfusions during the first 180 days after transplantation (P = .002) for the former group. The time to reach neutrophil counts of 0.5 and 1 x 10(9) neutrophils/L was 6 and 7 days shorter, respectively, in the BCT group than in the BMT group (P < 10(-5)). This quicker hematologic recovery was associated with a shorter length of hospitalization and a decrease in total cost of procedure during the first 6 months. Conclusion: This study establishes that allogeneic BCT results in quicker hematologic recovery but is associated with a higher occurrence of chronic graft-versus-host disease. J Clin Oncol 18:537-546. (C) 2000 by American Society of Clinical Oncology.