Vascular inflammation has been implicated in the progression of cardiovascular diseases such as atherosclerosis. In the present study, we found that HMC05, an extract from eight different herbal mixtures, dose-dependently inhibited tumor necrosis factor-α (TNF-α)-induced adhesion of monocytes to endothelial cells. Such inhibitory effect of HMC05 correlated with suppressed expression of monocyte chemoattractant protein-1, CC chemokine receptor 2, vascular cell adhesion molecule-1 and intercellular cell adhesion molecule-1. In addition, HMC05 significantly inhibited production of reactive oxygen species (ROS) and nuclear factor (NF)-κB activation by TNF-α. Those inhibitory effects of HMC05 (1-10 μg mL(-1)) on the TNF-α-induced inflammatory event was similar to those of berberine (1-10 μM), which is a major component of HMC05 and one of herbal compounds known to have vasorelaxing and lipid-lowering activities. However, berberine significantly reduced the viability of HUVECs in a time- and concentration-dependent manner. In contrast, HMC05 (1-10 μg ml(-1)) did not affect the cell viability for up to 48 h treatment. In conclusion, we propose that HMC05 may be a safe and potent herbal formula against vascular inflammation, and its action may be attributable to the inhibition of ROS- and NF-κB-dependent expression of adhesion molecules and chemokines.