The objectives were to determine the effects of alacepril, an angiotensin-converting enzyme inhibitor, on the expression of adhesion molecules and monocyte adherence to endothelial cells induced by 7-ketocholesterol (7-KC) and tumor necrosis factor (TNF)-alpha. We used human aortic endothelial cells (HAECs) and U937 monocytic cells. Surface expression and mRNA levels of intercellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule 1 (VCAM-1) were determined by EIA and RT-PCR. Adherence of U937 to HAECs was assessed by adhesion assay. Incubation of HAEC with 7-KC increased the surface expression of protein and mRNA levels of ICAM-1 and VCAM-1 on HAECs and the production of reactive oxygen species (ROS) in HAECs. Pretreatment with alacepril reduced the enhanced expression of these molecules in a dose-dependent manner. The inhibitory effect of alacepril against 7-KC or TNF-alpha-induced CAMs expression was stronger than that of captopril or enalapril. Alacepril inhibited the production of ROS in HAECs stimulated by 7-KC or TNF-alpha. These results suggest that alacepril works as anti-atherogenic agent through inhibiting endothelial-dependent adhesive interactions with monocytes induced by 7-KC and TNF-alpha.