Burr and Bun' (13,14) with fatfree diets for rats led, some 30 years ago, to discovery of the essential fatty acids (EFA). Lack of these acids in the diet causes development of the EFA-syndrome, which so far is best described in rats.The EFA deficiency in weanling rats is characterized by cessation of growth in about three months. Skin signs are scaliness of the tail and feet, dandruff, failure of yellow-brown pigment to develop on the back, rough