We have previously reported that recombinant human granulocyte colony-stimulating factor was well tolerated and resulted in sustained neutrophilia and improvement of neutrophil functions in newborn infants with presumed sepsis. We now report a 2-year follow-up on 21 of the initial cohort of 28 patients. Treatment with recombinant human granulocyte colony-stimulating factor in neonates with presumed sepsis was not associated with any long-term adverse hematologic, immunologic, or developmental effects.