Accumulation of monocyte-derived foam cells in focal areas of the arterial intima is one of the key events in early atherogenesis. We have examined the effect of lysophosphatidylcholine (lyso-PC; lysolecithin), a major phospholipid component of atherogenic lipoproteins, on the expression of adhesion molecules for monocytes, such as vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1), in cultured human and rabbit arterial endothelial cells. Cultured rabbit aortic endothelial cells treated with lyso-PC showed increased mRNA and cell surface expression of VCAM-1 and ICAM-1, which was associated with increased adhesion of monocytes and monocyte-like cells (THP-1, U937). In cultured human iliac artery endothelial cells, lyso-PC similarly induced both VCAM-1 and ICAM-1, whereas in umbilical vein endothelial cells only ICAM-1 was up-regulated. In all endothelial cells examined, the effect of lyso-PC on E-selectin (endothelial-leukocyte adhesion molecule-1) expression was negligible, thus differentiating this stimulus from other endothelial activators, such as interleukin 1, tumor necrosis factor, or lipopolysaccharide. We conclude that lyso-PC can selectively induce VCAM-1 and ICAM-1 in arterial endothelial cells and that this action, in addition to its monocyte chemoattractant activity, may play an important role in monocyte recruitment into atherosclerotic lesions.