The objective of this study was to investigate the effects of a lettuce (Lactuca sativa L.) extract on the inflammation of human umbilical vein endothelial cell (HUVEC) and blood lipid improvement in hypercholesterolemic mice fed a high cholesterol diet. The lettuce extract (100% ethanol extract) inhibited the expression of intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 in HUVEC treated with tumor necrosis factor-α (TNF-α). The lettuce extract suppressed the adhesion of THP-1 to TNF-α-treated HUVEC. The lettuce extract decreased the TNF-α-stimulated production of proinflammatory cytokine interleukin-6, interleukin-8 and chemokine monocyte chemotactic protein 1. In hypercholesterolemic mice, the lettuce extract reduced serum total cholesterol, triglyceride, and low-density lipoprotein-cholesterol level, while the lettuce extract elevated high-density lipoprotein-cholesterol level, resulting in the decrease of atherogenic index and cardiac risk factor level. These results suggested that lettuce extract can be an useful resource to show an anti-inflammatory effect and improve lipid metabolism