Despite the increasing use of peripheral blood progenitor cells (PBPC) instead of bone marrow (BM) for allogeneic hematopoietic stem cell transplantation (allo HSCT) from human leukocyte antigen (HLA)-matched unrelated donors in children, the relative benefits and risks of both stem cell sources in the pediatric setting remain largely unknown. Recently, the only larger study comparing the value of the 2 stem cell sources in a young patient group was confined to transplantation from HLA-identical sibling donors in older children and adolescents with acute leukemia. Based on the paucity of data in pediatric HLA-matched unrelated donor transplantation, we analyzed the outcome of 23 BM and 38 PBPC transplantations performed at our center. Neutrophil and platelet engraftment were achieved significantly faster in PBPC compared to BM recipients (18 versus 22 days and 26 versus 33 days; P < .001 and P = .03) whereas the risk for grade II-IV acute graft-versus-host disease (aGVHD) (62% versus 55%; P = .53) and chronic GVHD (cGVHD 65% versus 59%; P = .54) was comparable. As overall survival (OS; PBPC versus BM: 47.5% +/- 8.6% versus 51.8% +/- 10.5%; P = .88) and relapse-free survival (43.3% +/- 8.3% versus 51.8% +/- 10.5%; P = .60) are without detectable difference, PBPC and BM appear both as a valid stem cell source for HLA-matched unrelated donor transplantation in children with hematologic malignancies.