LOX-1 (lectin-like oxidized LDL receptor) is a newly identified cell surface receptor for oxidized LDL mainly expressed in endothelial cells. Recombinant soluble LOX-1(LOX-Fc) was generated by fusing the extracellular domain of LOX-1 with the Fc portion of IgG. A novel sandwich enzyme immunoassay specific for LOX-1 ligand is designed, using LOX-Fc and anti-apoB antibody. This immunoassay was used to determine LOX-1 ligand activity in normal and Watanabe heritable hyperlipidemic (WHHL) rabbit plasma. LOX-Fc was further applied for staining of atherosclerotic lesions of WHHL rabbits. LOX-I ligand levels were significantly elevated in the plasma of hyperlipidemic rabbits compared with controls. Furthermore, LOX-1 ligand activity was detected in the atherosclerotic lesions in situ. These results support the potential roles of LOX-1 interacting with its ligand in the pathogenesis of atherosclerosis, which is enhanced in hyperlipidemia.