Two yeasts (Saccharomyces fragilis and Saccharomyces lactis) were grown on deproteinated whey to yield com. quantities of the dried yeasts, which were analyzed to determine nutritional value for animals and man.Data are reported on gross composition, amino acids, lipids, fatty acids, choline, glutathione, and carbohydrates.The dried material contained about 47% protein, with sufficient of the essential amino acids to render it useful as a supplement for cereals.Feeding tests on pigs and calves yielded satisfactory results in terms of rate of weight gain and improved health.The dried yeast was also well accepted when introduced into the diet of man as a protein supplement in a number of situations: infants and adolescents, pregnant women, obese persons, the aged, and destitute individuals.