Abstract： Objective To evaluate theeffectiveness and safety of toremifene in treatment of premenopausal woman with moderate-severe cyclical mastalgia.Methods From April 2012toJanuary2013,112cases of premenopausal woman with moderate-severe cyclical mastalgiawere chosenas experimental objects,and weretreated with toremifene,40 mg/d,taken after dinner,treatment includes 3 menstrual cycle in Knot Prevention Institute of Binzhou Central Hospital.Breast pain,sex hormone,the occurrence of adverse reactions and endometrial thicknessbefore and after treatment were compared.Results After 3 menstrual cycle's treatment,83 cases(74.10%) of patients achieved effect in 112 cases of patients,and breast pain score decreased averagely (58.85±22.96)%. Progesterone,estradiol,luteinizing hormone and follicle stimulating hormone were increased after treatment,and had no significant difference compared to before(P>0.05).Endometrial thickness and the number of endometrial thickness≥5 mm had no significant difference compared to before(χ2=0.254,P>0.05). 25 cases(22.32%) of 112 cases patients occurred flushing hyperhidrosis,the incidence was higher than that of before,the difference was significant(χ2=13.515,P<0.05). Conclusion Toremifene could greatly improve clinical symptoms of moderate-severe cyclical mastalgia,and has few influence on sex hormone and adverse reactions,with high efficiency and safety.