Drug-induced agranulocytosis is a potentially fatal complication despite advances in supportive care. A patient with carbimazole-induced agranulocytosis associated with marked depletion of granulocytic precursors in the marrow was treated with granulocyte-macrophage colony stimulating factor (GM-CSF) at a dose of 5 micrograms/kg subcutaneously daily for one week. The absolute neutrophil count rose above 1 x 10(9)/L after one week of GM-CSF therapy. The GM-CSF probably expedited the recovery of the neutrophil count. Further studies are warranted to delineate the role of GM-CSF in the treatment of drug-induced agranulocytosis.