Abstract: Objective: To investigate the molecular mechanism behind Curcumin's anti-angiogenesis property. Methods: The anti-angiogenesis effect of curcumin on human umbilical vein endothelial cells (HUVEC) was studied using the MTT assay and flow cytometry (FCM). At different timepoints after curcumin treatment, Ang-1, Ang-2 and TSP mRNA levels were detected by RT-PCR and VEGF and MMP-9 protein expression levels were detected by Western blot using human lung adenocarcinoma A2 cells. Results: Curcumin inhibited HUVEC proliferation in a time/dose-dependent manner. Meanwhile,Curcumin induced HUVEC apoptosis, showing a higher apoptosis rate than the control (P<0.01). At different timepoints after curcumin treatment, Ang-1, Ang-2 and TSP mRNA levels and VEGF and MMP-9 protein expression levels in lung adenocarcinoma A2 cells decreased markedly. Conclusion:Curcumin inhibits angiogenesis via the following possible mechanisms: (1) by directly inhibiting vascular endothelial cell proliferation and enhancing cell apoptosis; (2) by inhibiting expression of pro-angio-genesis factors such as VEGF, Ang-1 and Ang-2; (3) by enhancing the expression of TSP, an anti-an-giogenesis factor; (4) by decreasing MMP-9 protein expression, thereby inhibiting extracellular matrix degradation.