A total of 889 cord blood samples collected from newborn infants of both sexes and 563 samples of venous blood collected from adult males in Iraq were examined for evidence of glucose-6-phosphate dehydrogenase (G6PD) deficiency. The deficiency was proved to exist in all ethnic groups in Iraq and in both adult males and infants. The overall incidence of the deficiency was 8.9% in the adults and 8.4% in the infants. The difference is not statistically significant. Evidence is given to suggest that favism ("khsaissa") is known to the people of southern Iraq.