Abstract-The role of hepatic lipase as a multifunctional protein that modulates lipoprotein metabolism and atherosclerosis has been extensively documented over the last decade. Hepatic lipase functions as a lipolytic enzyme that hydrolyzes triglycerides and phospholipids present in circulating plasma lipoproteins. Hepatic lipase also serves as a ligand that facilitates lipoprotein uptake by cell surface receptors and proteoglycans, thereby directly affecting cellular lipid delivery. Recently, another process by which hepatic lipase modulates atherogenic risk has been identified. Bone marrow transplantation studies demonstrate that hepatic lipase present in aortic lesions markedly alters aortic lesion formation even in the absence of changes in plasma lipids. These multiple functions of hepatic lipase, which facilitate not only plasma lipid metabolism but also cellular lipid uptake, can be anticipated to have a major and complex impact on atherogenesis. Consistently, human and animal studies support proatherogenic and antiatherogenic roles for hepatic lipase. Key Words: transgenic mouse models Ⅲ lipolytic enzyme Ⅲ ligand-binding function Ⅲ macrophages Ⅲ bone marrow transplantation Ⅲ aortic atherosclerosis C oronary artery disease (CAD) is a major cause of mortality in advanced societies. 1-3 Multiple factors contribute to the formation of lesions that ultimately lead to CAD. One of the initial events in the development of atherosclerosis is the accumulation of cells containing excess lipids within the arterial wall. 4 Plasma lipoproteins play a major role in the deposition and removal of lipids that accumulate in atherosclerotic lesions. Apolipoprotein B (apoB)-containing lipoproteins and high-density lipoprotein (HDL) have opposite effects on CAD and are independent risk factors for this disease. [5][6][7] Both classes of lipoproteins have been major targets for the development of new therapeutic approaches for treatment of CAD.During the last decade, a great deal of interest has focused on hepatic lipase and its impact on lipoprotein metabolism, including intermediate-density lipoproteins (IDLs), chylomicron remnants and HDLs, and atherogenesis. Hepatic lipase has been shown in several studies to modulate atherogenic risk; however, its role as either a protective or proatherogenic agent remains unclear. Published human and animal studies support proatherogenic and antiatherogenic functions for hepatic lipase. 8 -14 In humans, low hepatic lipase activity has been associated with increased risk of CAD. [15][16][17][18] Furthermore, premature CAD has been reported in patients with complete hepatic lipase deficiency, 19 although the manner in which these very few individuals have been identified raises the issue of ascertainment bias. Other studies have concluded that decreased hepatic lipase activity does not influence susceptibility to CAD. 20 Finally, increased hepatic lipase activity has been reported in patients with CAD. 21,22 A proatherogenic role for hepatic lipase has been suggested from the inverse corre...