The exudative diathesis, characteristic of vitamin E deficiency in chicks, readily occurs with diets containing 5% of fresh cod liver oil, slightly rancid cod liver oil, or a mixture of fresh and completely rancid cod liver oil; and to a lesser extent by similar proportions of lard or fatty acids from linseed oil. On the other hand, the symptoms do not occur if the diet contains a similar proportion of oleic acid or thoroughly rancid cod liver oil, or if the diet is rigidly freed of fats. These observations indicate that the appearance of symptoms of increased capillary permeability is dependent upon the presence of highly unsaturated fatty acids in the vitamin E deficient diet, and that rancidity of the dietary fat does not contribute to the development of the symptoms.