IN A previous study (Ingle, Li and Evans, 1946) it was shown that the administration of pure adrenocorticotrophic hormone (ACTH) to normal rats force-fed a high carbohydrate diet caused hyperglycemia and glycosuria with an accompanying increase in the excretion of nitrogen and potassium and inhibition of growth. In the present experiments a comparison was made of the metabolic responses of normal rats to ACTH as related to the type of diet. During the administration of ACTH some of the animals on the high carbohydrate diet developed glycosuria. All of the animals showed inhibition of weight gains and an increase in urinary nitrogen, the most marked changes occurring in the high fat series and the least marked changes in the high protein series. The accompanying rise in urinary potassium was not clearly related to the nature of the diet. There were small, temporary increases in the excretion of sodium and chloride which may have been insignificant.