Granulocyte colony stimulating factor (G-CSF) treatment was successfully used in three preterm infants with alloimmune neonatal neutropenia (AINN). Two infants had persistent neutropenia despite treatment with intravenous immunoglobulin and random donor granulocyte transfusions for presumed sepsis. Neutrophil counts returned to normal with G-CSF treatment; the response was least convincing in one infant with fulminant necrotising enterocolits. It is suggested that treatment with G-CSF be considered early for the treatment of infants with AINN.