Abstract SEVERAL investigators have made extensive studies of gizzard erosion in growing chickens. Dam (1929, 1930, 1934a, 1934b, 1935) and Almquist and Stokstad (1935a, 1935b) observed the condition in chickens fed vitamin K-deficient diets. Almquist and Stokstad (1936a, 1936b) concluded that it is not due to a deficiency of vitamin K but of an unidentified fat-soluble factor. Later Almquist (1938) reported beneficial results were obtained from feeding bile, bile acids, or bile salts to growing chickens. Bird and co-workers (1938) reported that chondroitin is effective in preventing gizzard erosion but Crandall and co-workers (1939) could not confirm this. Lansing, Miller, and Titus (1939) and Miller and Titus (1942) found that a very high percentage of chicks are hatched with deposits of extravasated blood in or under their gizzard linings. Inasmuch as they concluded that these deposits of extravasated blood develop into erosions in the growing chickens, it was desirable to study . . .