Recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) was given to an intensive-care patient with polytrauma in a life-threatening situation with acquired agranulocytosis and sepsis. Mature granulocytes reappeared in the blood 2 days after initiation of rhGM-CSF therapy; granulocyte precursors peaked at 43% after 5 days. Bone marrow examination performed 7 days after the beginning of rhGM-CSF therapy revealed complete regeneration of granulopoiesis. The functional analysis of these blood leukocytes in vitro showed regular production of reactive oxygen radicals. Clinically, the patient recovered without any serious side effects due to the rhGM-CSF therapy. These results suggest that rhGM-CSF accelerates granulocyte recovery from acquired agranulocytosis with the presence of their functional activity.