The object of this investigation was to study the effectiveness of varying amounts of taurocholate and of high doses of other unconjugated and conjugated bile salts on the appearance of 4- 14C-cholesterol in the lymph. A preparation was used which consists of a modification of Bollman's technique for the cannulation of the abdominal thoracic duct in the rat; a uniform lymph flow rate was assured by infusion of isotonic saline at a constant rate into the duodenum. Experimentally, individual unconjugated or conjugated bile salts were administered by stomach tube in an emulsion containing protein, carbohydrate, monoolein, and 4- 14C-cholesterol. Lymph was collected hourly for at least 12 hr after feeding. The radioactivity of free cholesterol and cholesterol esters was analyzed in a liquid scintillation counter after separation by glass fiber paper chromatography. The appearance of both dietary and endogenous cholesterol in the thoracic duct lymph, measured 6 hr after feeding, was related to the type of bile salt administered with the emulsion. In experiments in which only a trace amount of 14-cholesterol was fed, the critical micellar concentration of taurocholate was produced by administration of 225 mg or more of the bile salt. Taurocholate supported the absorption of total cholesterol similarly to that observed with natural bile. In addition, taurocholate was the most effective bile salt in aiding cholesterol absorption. Glycocholate and glycodeoxycholate were significantly less effective than the corresponding taurine conjugates. Absorption was not enhanced by combining bile salts in various proportions as to make a total of 250 mg. After administration of 3α,7α,12α-trihydroxy-5β-unconjugated and conjugated bile salts, 65–75% of the cholesterol in the lymph was found to be esterified. Both 3α, 12β-dihydroxy-5β- and 3α,7α-dihydroxy-5β-conjugated bile salts were capable of activating the absorption mechanism, but they supported the esterification of only 50% of the exogenous or endogenous cholesterol in the lymph. Esterified cholesterol almost disappears from the lymph of those animals dosed with taurodeoxycholate. These findings have been interpreted as indicative that certain specific conjugated bile salts play a special role in the esterification of the sterol during intestinal absorption and that the appearance of unesterified and of esterified cholesterol in the lymph is the result of at least two independent mechanism. After feeding the same emulsion with either natural bile, taurocholate, or glycocholate and a trace dose of oleic acid-9,10- 3H, biphasic kinetics for the appearance of radioactive triglycerides in the lymph was demonstrated.