ApoA-I is a 29.0 kDa protein produced in the liver and intestine, and secreted as the predominant constituent of nascent high-density lipoprotein (HDL) particle. ApoA-I, which is found exclusively in HDL, has a unique ability to capture and solubilize free cholesterol. This apoA-I ability enables HDL to remove excess peripheral cholesterol and return it to the liver for recycling and excretion. This process, called reverse cholesterol transport, is though to inhibit atherogenesis. For this reason HDL is also known as the ``good cholesterol.'' The therapeutic potential of apoA-I has been recently assessed in patients with acute coronary syndromes, using a recombinant form of a naturally occurring variant of apoA-I (called apoA-I Milano). The availability of recombinant normal apoA-I should facilitate further investigation into the potential usefulness of apoA-I in preventing atherosclerotic vascular diseases. Recombinant human ApoA-I is a 28.2 kDa protein of 244 amino acid residues.