Aim: Gambogic acid (GA) is the major active compound of Gamboge, a brownish or orange resin exuded from Garcinia hanburryi tree in Southeast Asia. Previous studies have demonstrated that GA exhibits potent anticancer effects by inducing cell cycle arrest or apoptosis in many types of cancer cell lines and blocking angiogenesis via inhibition of vascular endothelial cell proliferation and migration. Proliferation and migration of vascular smooth muscle cells (VSMCs) are critical steps in the progress of atherosclerosis and restenosis after angioplasty. In the present study, we investigated whether GA has an inhibitory effect on the proliferation and migration of VSMCs and its possible mechanism. Methods: The inhibitory effect of GA on the proliferation induced by PDGF-BB and EGF was measured by using Cell number counting assay and [