same iron intake. This study suggests that factors in the diet other than the amount of iron are important in the etiology of iron deficiency.Occult blood loss,12 albuminlosing enteropathy,3 and other alterations of gastrointestinal func¬ tion4 have been described in about half of the infants with severe iron deficiency who were studied. Evi¬ dence has been presented that fresh cow's milk plays an etiologic role in the development of the altered in¬ testinal physiology.-:l If the effects of feeding fresh cow's milk to the infant are not due to some factor of peculiar susceptibility, it should be possible to demonstrate these effects in a rela-