Work in this and other laboratories suggests an interrelationship between vitamin A and cholesterol metabolism( 1-4). However, the effect of estrogens upon this interrelationship is not clearly understood, although certain relations have been observed. A review by Moore(5) suggests that under the same conditions female rats seem to store more vit. A in their livers than do males, while male rats seem to have higher blood levels of this vitamin than females. Male rats have also been shown to store significantly more cholesterol in their livers than females(6). Extradiol has been reported to increase the serum vit. A level in sexually immature pullets( 7) and liver vit. A concentration in male rats( 5) , and to increase the serum and liver cholesterol concentration in male rats (8,9). Castration of male rats has been shown to decrease the amount of vit. A circulating in the blood and stored in the liver when no dietary cholesterol was fed or when cholesterol and vit. A were given together in the diet(2). Castration of male rats also has been shown to decrease the liver cholesterol deposits ( 10) and serum cholesterol levels ( 1 1 ) .This study reports the effect of one level of estradiol benzoate on the interrelationship between vit. A and cholesterol metabolism.Procedure. Weanling male rats of the Sprague-Dawley straint were depleted of their vit. A stores on purified diets,$ previously described( 4), complete in all requirements except vit. A. As each animal mani-