Granulocyte colony-stimulating factor (G-CSF) is often administered after hematopoietic-cell transplantation (HCT) to accelerate neutrophil recovery, but it is unclear what impact G-CSF has on long-term transplantation outcomes. We analyzed within the database of the Center for International Blood and Marrow Transplant Research the impact of giving posttransplantation G-CSF on the outcomes of allogeneic HCT for acute myelogenous leukemia and chronic myelogenous leukemia in 2719 patients who underwent transplantation between 1995 and 2000. These included 1435 recipients of HLA-identical sibling bone marrow (BM), 609 recipients of HLA-identical peripheral-blood stem cells (PBSCs), and 675 recipients of unrelated donor BM transplants. Outcomes were compared between patients receiving or not receiving G-CSF within 7 days of HCT according to graft type. Median follow-up was more than 30 months (range, 2-87 months). G-CSF shortened the posttransplantation neutropenic period, but did not affect days +30 and +100 treatment-related mortality (TRM). Probabilities of acute and chronic graft-versus-host disease (GVHD), leukemia-free survival (LFS), and overall survival were similar whether or not G-CSF was given. Multivariate analyses confirmed that giving G-CSF did not affect the risk of GVHD, TRM, LFS, or survival. In conclusion, results of this study found no long-term benefit or disadvantage of giving G-CSF after transplantation to promote hematopoietic recovery.