Objective To explore the effect of toremifene on estrogen receptor （ER） expression and tumor micro-angiogenesis in rat Lewis lung carcinoma. Methods Cell suspension of rat Lewis lung carcinoma was implanted into 40 female Wistar rats subcutaneously. The rats were randomly divided into a control group，a estradiol group （0.006 mg/mL），a low dose toremifene group （0.25 mg/mL） and a high dose toremifene group （5 mg/mL）. Tumor size was measured every 3 days and the tumor growth curve was charted. On 15th day，the tumor weight and the growth inhibition rate were measured. Immunohistochemical method was used to detect the expressions of estrogen receptor α （ERα），estrogen receptor β （ERβ），vascular endothelial growth factor （VEGF），and platelet endothelial cell adhesion molecule-1 （PECAM-1）. Integral optical density （IOD） of ERα，ERβ and VEGF was calculated by image analysis software. Quantitative method of Weidner with PECAM-1 was employed for microvessel density （MVD） count. Results Tumor size of the four groups all presented a quadratic function growth trend with time （Plt;0.05）. Tumor growth speed was slower in toremifene groups of low and high doses than that in the control group and the estradiol group. The growth inhibition rate of the estradiol group，the low dose toremifene group and the high dose toremifene group was －15.1%，22.6%，and 45.1%，respectively. The expressions of ERα，VEGF，and MVD in the estradiol group were significantly higher than those in the control group，the low dose toremifene group and the high dose toremifene group （all Plt;0.05）. The expressions of ERα，VEGF，and MVD in the low dose toremifene group were significantly lower than those in control group，but higher than those in high dose toremifene group （all Plt;0.05）.The expression of ERα was positively related to VEGF （r=0.664，Plt;0.05） and MVD（r=0.593，Plt;0.05）. Conclusion Toremifene can inhibit tumor growth，which maybe involved in inhibiting ERα mediated VEGF expression.