To investigate the preventive effect of the compounds against atherosclerosis, we pretreated human umbilical vein endothelial cells (HUVECs) with 30 μM of procyanidin dimers (Pro A1, Pro A2, Pro B1 and Pro B2), monomers ((−) epicatechin and (+)-catechin) or their microbial metabolites including DHPV, DHPA and DHAA for 1 h prior to the tumor necrosis factor (TNF)-α stimulation. The gene discussed is TNF; the disease is atherosclerosis.