The regulation of cholesterol ester metabolism was studied using cell suspensions of capsular and decapsulated portions of rat adrenal glands. The cell suspensions were prepared using collagenase as a dispersing agent, and incubations were performed in Krebs-Ringer buffer containing 0.1% albumin. The cellular uptake and esterification of exogenously added labeled oleic acid was time and temperature dependent in both capsular and decapsulated cell preparations. Synthetic ACTH caused a decrease in cholesterol ester incorporation with capsular preparations, while no net change was observed in cells from decapsulated adrenal tissue. An increase in oleic acid incorporation into cholesterol esters was observed for both cell preparations when aminoglutethimide was added, particularly in the presence of ACTH. A similar increase was seen with cycloheximide. Corticosterone production, which was stimulated 5–20-fold by ACTH, was reduced to control levels with addition of aminoglutethimide or cycloheximide. When cholesterol was used as labeled substrate, ACTH and aminoglutethimide caused changes in cholesterol esterification similar to those observed with oleic acid. Angiotensin II had no appreciable effect on cholesterol esterification and did not influence corticosterone production. These studies suggest that cell suspensions can be used to study the role of cholesterol ester metabolism in regulating the steroidogenic response of the adrenal gland to ACTH. (Endocrinology93: 1163, 1973)