Objective To investigate the inhibition effects of chitooligosaccharides on the production of pro-angiogenesis factors of estradiol(E2) induced human MCF-7 cells.Methods The cell survival rate was demonstrated by MTT assay at 24 and 48 hours;and the mRNA level of some pro-angiogenesis factors such as MMP-9,TIMP-1,2 and VEGF were investigated by RT-PCR.Results There was no significant effect of chitooligosaccharides on proliferation of human MCF-7cells;but when induced by E_2,MMP-9 was significantly down-regulated by chitooligosaccharides.Conclusion Chitooligosaccharides had potent inhibition effects on the mRNA production of MMP-9 of human MCF-7 cells.