A cellular defect associated with decreased bactericidal activity of the polymorphonuclear leukocyte has been found in a 2½ yr old Negro boy with the typical clinical and pathological findings of chronic granulomatous disease. Unlike previously described patients his polymorphonuclear leukocytes were shown to undergo apparently normal degranulation and vacuole formation after phagocytosis. Metabolic studies of the leukocytes indicated a failure to increase oxygen consumption with phagocytosis or to reduce Nitroblue tetrazolium dye. These metabolic abnormalities are identical with those previously reported in patients with chronic granulomatous disease. Two additional patients with chronic granulomatous disease have also been found to have apparently adequate degranulation of polymorphonuclear leukocytes after phagocytosis. Our studies suggest that failure of degranulation may not be a necessary part of this functional leukocyte abnormality.