Expression of cell adhesion molecules by endothelium and the attachment of monocytes to endothelium may play a major role in atherosclerosis. Ellagic acid (EA) is a phenolic compound found in fruits and nuts including raspberries, strawberries, grapes and walnuts. Previous studies have indicated that EA possesses antioxidant activity in vitro. In the present study, we investigated the effects of EA on the formation of intracellular reactive oxygen species, the translocation of NFkappaB and expression of vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 and endothelial leucocyte adhesion molecule (E-selectin) induced by IL-1beta in human umbilical vein endothelial cells (HUVEC). We found that EA significantly reduced the binding of human monocytic cell line, U937, to IL-1beta-treated HUVEC. The production of reactive oxygen species by IL-1beta was dose-dependently suppressed by EA. Supplementation with increasing doses of EA up to 50 micromol/l was most effective in inhibiting the expression of VCAM-1 and E-selectin. Furthermore, the inhibition of IL-1beta-induced adhesion molecule expression by EA was manifested by the suppression of nuclear translocation of p65 and p50. In conclusion, EA inhibits IL-1beta-induced nuclear translocation of p65 and p50, thereby suppressing the expression of VCAM-1 and E-selectin, resulting in decreased monocyte adhesion. Thus, EA has anti-inflammatory properties and may play an important role in the prevention of atherosclerosis.