A variety of leukocyte enzyme activities were studied in an 11-year-old female with chronic granulomatous disease (CGD) and several members of her family. Leukocyte glucose-6-phosphate dehydrogenase (G-6-PD) activity was 17 nmol/min/mg protein in the patient; two brothers with symptoms of recurrent bacterial infections have G-6-PD activities of 58 and 37 nmol/min/mg protein; the activites of this enzyme in both parents, maternal grandmother, and one additional brother were within normal limits. Storage at 4 degrees or heating at 37 degrees over a 120-min period revealed a marked lability of G-6-PD activity in the patient's cells which could not be stabilized by the addition of NADP and 2-mercaptoethanol; this lability was not seen in other family members tested. Activities of leukocyte glutathione reductase were reduced in both parents and the two affected male siblings with values of 18, 23, 23, and 24 nmol/min/mg protein, respectively. Activities of leukocyte glutathione peroxidase were reduced in all of the immediate family members tested, with values ranging from 11.2 to 43 nmol/min/mg protein; the activity of this enzyme in the patient was 38.5. Leukocyte NADP content in the patient, father, and two affected male siblings were 16.5, 23.4, 22.2, and 28.2 nmol/15 min/10(7) leukocytes, respectively.