Abstract: Objective To study the effects of enviromental estrogen chemicals octylphenol(OP)and genistein(GEN)on the expressions of vascular endothelial growth factor(V EGF),V EGF receptor(flk-l)and CXC chemokine receptor type 4(CXCR4)in rat breast cancer.Methods Female Sprague-Dawley rats were randomly divided into control,model,GEN treated,OP treated and GP(GEN+OP)treated group.After 7,12-dinmethylbenzaanthracene(DMBA)induced rat breast cancers(Except rats in control group),rats were killed on day 210.Western blotting and immunohistochemistry methods were used to detect the expressions of V EGF,CXCR4 and flk-1 on normal mammary grand and mammary cancers.Results Compared with model group,V EGF,CXCR4 and ilk-1 expressions were significantly decreased in mammary cancers of genistein treated group,while they were significantly increased in octylphenol treated group.CXCR4 expression was significantly decreased in GP treated group.Conclusion GEN is down-regulate V EGF,CXCR4 and flk-1 expressions in mammary cancer then may inhibits the incidences of DMBA-induced mammary cancers.OP is up-regulate V EGF,CXCR4 and flk-1 expressions in mammary cancer then may increase the incidences of DMBA-induced mammary cancers.