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It has recently been reported by Torii(1951)of this laboratory that the injection of alloxan to the rat was followed by a prompt and definite fall of the adrenal cholesterol content, especially ester cholesterol, but the levels of cholesterol in other tissues were nearly unchanged. These facts suggest strongly that there may exist an intimate relation between the initial hyperglycemia in the alloxan rat and an abnormal activity of the pituitary-adreno-cortical hormones.The earlier work of Long et al. (1946)has shown that the injection of adrenocorticotropic hormone of the pituitary in rats has been found to lower the cholesterol content of the adrenal glands.The reports by Constantinides(1950)and Shephered, Smith and Longwell (1952)elucidated the relation between the carbohydrate metabolism and the activity of adrenal cortical actions on the changes of the adrenal cholesterol content.Longwell et al. has pointed out the facts that by the exposure to cold a marked decrease of the adrenal cholesterol in fasted normal and non-fasted diabetic rats, but less so in non-fasted normal rats, and furthermore revealed that the cold exposure caused a decrease of adrenal ascorbic acid in both normal and diabetic rats without preliminary fasting.From these results they concluded that by the measurment of the adrenal cholesterol content, the response of the adrenal gland to cold, is related to the glycogenesis of the liver.Since depletion of adrenal cholesterol in the alloxan diabetic rats is of some interest, the author has carried out the same experiment with the use of rabbits, and has found, as described in this paper, that the adrenal cholesterol reached to the lowest level at the stage of hypoglycemia and returned to the control value at the final hyperglycemic stage.With regard to the depletion of adrenal cholesterol in alloxan hypoglycemia, it would be interest to decide whether a large loss of adrenal cholesterol in the alloxan hypoglycemic rabbits is due to some specific effect of hypoglycemia, following the depletion of glycogen in the liver or to the specific effect of pituitaryadreno-cortical hormones.Received for publication Dec. 7, 1955. FURUBAYASHI METHODMale rabbits, 1.8 to 2.3kg., were used. The hypoglycemic shock were produced by the intravenous injection of alloxan(150mg.per kg. of body weight), hydrazine sulphate (100mg. do.), guandine(300mg. do.), or insulin(2 unit do.). Blood samples were taken from the heart, and the free and total cholesterol of serum were estimated by the method of Bloor, before and after the hypoglycemic convulsion or following the injection of various hormones.The weighed samples of various tissues were macerated with sand and the cholesterol extraction was done three times repeatedly with alcohol.After the total cholesterol samples were saponified, either from the original or from the saponified samples, cholesterol was precipitated as its digitonide. The digitonide thus obtained was purified with petroleum ether, and further procedure was carried out by the method of Kelsey(1939)...