The objectives of this research are to develop valid bioassays for "available iron" in foods and food products utilizing experimental animals, to apply these methods to a variety of products, and to further evaluate iron deficiency produced under various conditions in experimental species. The latter studies include further investigation of the nature and cause of a lipemia which develops in anemic chicks and rats, the apparent strain and sex differences in the response of rats to iron deficient diets, and the development of iron deficiency in infant monkeys, especially when fed whole milk diets.