We compared the effects of genistein and daidzein on the expression of chemokines, cell adhesion molecules (CAMs), and endothelial nitric oxide synthase (eNOS) in tumor necrosis factor (TNF)-${alpha}$-stimulated human umbilical vascular endothelial cells (HUVECs). TNF-${alpha}$ exposure significantly increased expression of monocyte chemoattractant protein (MCP)-l, vascular adhesion molecule (VCAM)-1, and intercellular adhesion molecule-1. Genistein significantly decreased MCP-l and VCAM-l production in a dose-dependent manner, whereas CAM expression was not significantly lowered by genistein treatment. However, daidzein slightly decreased MCP-l production. The effects of genistein and daidzein on MCP-l secretion coincided with mRNA expression. Pre-treatment with either genistein or daidzein elevated eNOS expression and nitric oxide production disturbed by TNF-${alpha}$ exposure. A low concentration of isoflavones significantly inhibited nuclear factor (NF)${kappa}$B activation, whereas a high dose slightly ameliorated these inhibitive effects. These results suggest that genistein had a stronger effect on MCP-l and eNOS expression than that of daidzein. Additionally, NF${kappa}$B transactivation might be partially related to the down-regulation of these mRNAs in TNF-${alpha}$-stimulated HUVECs.