Objective: The cardioprotective role of HDL is thought to be related to the role of HDL in reverse cholesterol transport. Preβ-HDL is a key accepter of peripheral cellular cholesterol. Apolipoprotein M(ApoM) is a novel human apolipoprotein which is mainly associated with HDL. By influencing preβ-HDL formation and cholesterol efflux, apoM is thought to be an important regulative factor in HDL metabolism and affects on the initiation and developmet of atherosclerosis. However, it has not yet entirely clear that apoM involved in removal of metabolic process. In this study, we investigated clearance and distribution of apolipoproteinM in rat.Methods: Clearance and distribution of apoM in vivo was studied by injecting purified ~(125)I-labeled apoM into the circulation of the animals through a tail vein and then taking periodic blood samples and different organs.Results: The results showed that concentration-time curves after the venous injection ~(125)I-labeled were fitted to a two-compartment model of pharmacokinetics. T1/ 2 (α) = 0. 485 h, T1/ 2 (β) = 9.680 /h, FCR = 11.960/h. The radioactivity in different organs after the venous injection of ~(125)I-apoM showed that the stomach contained higher radioactity than that in other organs.Conclusions: In the present study, we demonstrate that the concentration-time profile after the venous injection of ~(125)I-apoM was discribed by a two-compartment model. There might be some specific binding sites for apoM in stomach. It is possible that stomach is a novel target organ..