RhGM-CSF is a hematopoietic growth factor which stimulates the proliferation, differentiation and functional activity of neutrophils, monocytes and macrophages. It also stimulates proliferation of endothelial cells and induces the production of other cytokines, such as interleukin (IL-1), tumor necrosis factor (TNF), interferon, prostaglandin E2, and plasminogen activating factor which affects both hematopoietic and non-hematopoietic cell activities. Initial clinical studies in 1987 generally excluded experimental therapy with rhGM-CSF in pediatric patients (age < or = 17 years) unless life threatening illness related to neutropenia and infection developed (i.e., patients with graft failure). Serious complications of patients undergoing autologous bone marrow transplantation (BMT) related to pancytopenia include infection and hemorrhage. Other regimen related complications include venooclusive disease, pneumonitis and mucositis. As a result of these complications, patients require intensive medical support including antibiotics and hyperalimentation. Initial hospital duration following marrow reinfusion is generally 4 to 5 weeks. Hematopoietic growth factors have been administered to patients undergoing autologous BMT as an attempt to reduce regimen related toxicity.