Apolipoprotein AI (Apo AI), constituting 75% of HDL-associated apolipoproteins, is critical for reverse cholesterol transport (RCT), mediating cholesterol efflux from peripheral tissues to the liver. As the primary structural component of HDL, Apo AI stabilizes discoidal HDL particles, activates lecithin-cholesterol acyltransferase (LCAT) to esterify cholesterol, and facilitates HDL maturatioN. Its anti-inflammatory properties include blocking T-cell–monocyte interactions, reducing TNF-α and IL-1β production, and neutralizing oxidized LDL. Apo AI concentrations are inversely correlated with coronary heart disease (CHD) risk.