Purpose For recipients of allogeneic hematopoietic stem-cell transplantation (alloHSCT), we hypothesized that prophylactic therapy during neutropenia with granulocyte-macrophage colony-stimulating factor (GM-CSF) decreases invasive fungal disease (IFD). Patients and Methods We randomly assigned 206 patients undergoing alloHSCT to receive once-daily subcutaneous GM-CSF (5 to 7 g/kg per day), granulocyte colony-stimulating factor (G-CSF; 5 to 7 g/kg per day), or a combination of G-CSF and GM-CSF (2 to 3 g/kg per day each). Treatment was started on day 5 after transplantation and was continued until the absolute neutrophil count was 1.5 x 10(9)/L for 2 consecutive days. The primary outcomes were 100-day incidence of proven and probable IFD and response rate of antifungal treatment. Results For the intent-to-treat population, there was no significant difference in 100-day incidences of proven and probable IFD among the three groups. The antifungal treatment response was better in the GM-CSF group and G-CSF+GM-CSF group than in G-CSF group from day 22 to day 100 (P = .009). The 100-day cumulative mortality after transplantation was lower in the GM-CSF group than in the G-CSF group (10.3% v 24.6%, respectively; P = .037). The GM-CSF and G-CSF+GM-CSF groups had lower 100-day transplantation-related mortality than the G-CSF group (8.8%, 8.7%, and 21.7%, respectively; P = .034). After a median follow-up of 600 days, IFD-related mortality was lower in the groups that received GM-CSF or G-CSF+GM-CSF compared with G-CSF (1.47%, 1.45%, and 11.59%, respectively; P = .016). There were no significant differences in relapse, graft-versus-host disease, or hemorrhage-related mortality among the three groups of patients. Conclusion For recipients of alloHSCT, compared with G-CSF, prophylactic GM-CSF was associated with lower 100-day transplantation-related mortality, lower 100-day cumulative mortality, and lower 600-day IFD-related mortality. (C) 2015 by American Society of Clinical Oncology