The relationship between the features of bone marrow donor and the quality of marrow harvest has been unclear because most of bone marrow registries have multiple collection centers with somewhat different harvest procedures. We are able to address this issue for Tzu Chi General Hospital is the only collection center affiliated with Tzu Chi Taiwan Bone Marrow Registry. Between November 1997 and March 2002, data of 286 healthy unrelated donors was analyzed to correlate with the cell density of total nucleated cell in bone marrow harvests. The harvest procedure was standardized by single-hole harvest needle under general anesthesia. The operation staffs were restricted within the members of Oncology-Hematology division. The results showed that the cell density of bone marrow harvest was positively correlated with donor body weight and peripheral white blood cell count P = 0.0475, P < 0.0001, but negatively correlated with the total volume of bone marrow harvest P < 0.0001. We recommend that if multiple human leukocyte antigen-matched donors are available, donor with higher body weight and/or higher white blood cell count be selected for allogeneic bone marrow transplantation.