Abstract: Objective To investigate the effects of different menstrual cycles on dynamic contrast-enhanced breast MRI. Methods Dynamic contrast-enhanced breast MRI was performed in 16 females at the late extravotory phase（within 1 week before menstrum） and early proliferation phase（within 1 week after menstrum） of menstrual cycle using the same image protocol.BI-RADS-MRI was double-blindly categorized and early 90s enhancement ratio was detected.Differences in the two phases were compared. Results The number of lesions categorized as 4,3 and 2 was 19,97 and 68,respectively,at the late extravotory phase and 8,62 and 42,respectively,at the early proliferation phase.The early 90s enhancement ratio was（114.1±17.6）%,（69.2±15.2）%,respectively（P＜0.01）. Conclusion Dynamic contrast-enhanced breast MRI at the early proliferation phase can decrease BI-RADS-MRI categories and its false positive prediction.