Phase I, II trials indicate that Recombinant human granulocyte macrophage colony stimulating factor (rhGM-CSF), stimulates recovery of neutrophils following myelosuppressive chemoradiotherapy. In Seattle it was administered to patients undergoing autologous bone marrow transplant (ABMT) for lymphoid malignancy. The data indicate that rhGM-CSF was well tolerated and associated with earlier neutrophil recovery, fewer infections and shorter initial hospital duration. Survival was not improved, however, less regimen-related toxicity was observed. Studies in patients with marrow graft failure are strongly suggestive of improved survival and rhGM-CSF is recommended for therapy in those patients. Although numbers were small, results in pediatric patients were not significantly different than results in adults.