Nine low birth weight infants with neutropenia born to mothers with preeclampsia were treated with granulocyte-colony stimulating factor, 10 micrograms/kg intravenously, within 24 hours of birth and at 24-hour intervals for a maximum of three doses if neutropenia persisted. The absolute neutrophil count increased significantly in eight of the nine infants within 6 hours, and neutrophilia was sustained for at least 72 hours after administration of a single dose of granulocyte-colony stimulating factor.