In an attempt to determine whether ironfortified infant formulas produced gastrointestinal symptoms in infants, we fed two similar formulas, one with and one without iron fortification, to a group of 93 term infants upon discharge from the nursery on the third day of life. Infants were fed the formulas for a period of 42 days while their mothers kept detailed daily records of all gastrointestinal symptoms. A total of 49 infants were fed the non-iron-fortified formula and 44 infants were fed the iron-fortified formula. Review of the records revealed no differences in the number of stools per day, the description of the stools, the number of days without stools, the incidence or frequency of colic, spitting-up, or vomiting. We conclude that the feeding of iron-fortified formulas to infants does not produce an increased incidence of gastrointestinal symptoms or signs.