Ursolic acid (UA) has been implicated as one of the major components of traditional medicinal plants. In this study, we investigated the effect and mechanisms of UA, by comparison with other triterpenes, Glycyrrhetic acid (GA), Oleanolic acid (OA), Uvaol (Uv) and alpha-amyrin on the vascular cell adhesion molecule-1 (VCAM-1) in Human Umbilical Vein Endothelial Cells (HUVECs). UA inhibited the induction of the VCAM-1 expression in a dose-dependent manner after stimulation with TNF-alpha, whereas GA and OA did not show any inhibitory effect. Furthermore, UA inhibited the adhesion of HL-60 to the TNF-alphastimulated HUVECs. The activity difference indicated that the ursane structures with a highly polar group at the 28-position are critical components of UA for regulating the VCAM-1 expression. These results suggested that the anti-inflammatory effect of the triterpenes might depend on their chemical structure.