Neutrophils from a boy with recurrent bacterial infections since infancy were found to have unique morphologic abnormalities. The nuclei were bilobed, and the cytoplasm appeared nearly devoid of granules in blood smears subjected to Wright-Giemsa stain. Neutrophil alkaline phosphatase activity was absent by histochemical staining. In ultrastructural studies of bone marrow, specific granules were found to be delayed in appearance and abnormal in structure. After the ingestion of Staphylococcus aureus by the cell, abnormal phagolysosomes were formed, and bactericidal function was impaired. The basic abnormality in this patient appears to be a congenital abnormality of specific granule formation. (N Engl J Med 290:478–484, 1974)