At present, the amount of selenium in infant formulas is not controlled and varies depending upon the selenium content of the raw materials used in its manufacture. Since selenium deficiency has been associated with two diseases of childhood, prudence dictates that the concentration of selenium in infant formula be standardized. Extrapolation from studies with human adults indicates that a daily intake of 10 microg of selenium is sufficient to meet the nutritional requirement of the infant while providing a reasonable margin of safety. Extrapolation from adult studies also suggests that intakes of 75-160 microg/d might have harmful effects in infants. On the other hand, no cases of selenosis in infants have been reported in high selenium areas of the United States, where human breast milk supplies as much as 47 microg/d. Therefore, it is proposed that infant formulas contain enough selenium to provide 10-45 microg/d.