An attempt has been made to determine if the high mortality of the suckling young of milk fed rats is due to a deficiency of the antineuritic vitamin content of the milk. Stock-fed rats, either just previous to or following parturition, were given various types of milk diets, some of which were distinctly lower in the antineuritic vitamin than others. The influence of the addition of substances known to be rich in the vitamin was tested, as well as the influence of certain inorganic substances. The results of the investigation indicate that the less-than-optimum growth in some of the suckling young of the milk fed groups is not due to a deficiency of the antineuritic vitamin in the milk secretion, but to the inability of the particular rat to ingest a sufficient amount of milk to meet its caloric requirements, or to a general distaste for the food so that too little is eaten.