Ursolic acid (UA) and oleanolic acid (OA) were examined for anti-angiogenic activities by using the chick embryo chorioallantoic membrane (CAM) assay. The presence of UA or OA inhibited angiogenesis in a dose-dependent manner; the doses required for half-maximal inhibition (ID50) were 5 micrograms and 40 micrograms per CAM, respectively. UA was a more potent angiogenic inhibitor than OA. We also tested for inhibitory effect on the proliferation of bovine aortic endothelial cell. They effectively inhibited the proliferation of bovine aortic endothelial cell in a concentration-dependent manner. The IC50 values of anti-proliferative effects were determined to be 5 microM for UA and 20 microM for OA. Based on these results, we speculated that the inhibitory effects on bovine aortic endothelial cell proliferation of UA and OA might be important for anti-angiogenesis.