Abstract: Objective:To investigate the correlations between different periods of women's menstrual cycle and clinical characteristics(breast symptom,hormone level and ultrasonic image).Methods:The breast pain sign,levels of serum estradiol(E₂) and progesterone(P),and thickness of mammary gland,duct width,glandular structure and ADC detected by breast ultrasonography and MRI in 35 childbearing age women between 6 to 14 days of menstrualcycle(follicular phase) and 15 to 28 days menstrual cycle(luteal phase) were compared.Results:The levels of E₂,P,LH and ADC value in luteal phase were higher than those in follicular phase(P<0.05),and the width of duct in luteal phase was significant lower than that in follicular phase(P<0.05).The levels of E₂ and P at luteal and follicular phase were significantly related to the ADC value(P<0.05).In luteal phase,the levels of E₂ and P in the women with breast structure change and pain decreased and increased compared with the women without breast structure change and pain,respectively(P<0.05 to P<0.01).In follicular phase,the level of P in the women with breast structure change was significant higher than that in women without breast structure change(P<0.01),and the levels of E₂ and P in the women with breast tenderness were higher than those in women without breast tenderness(P<0.05 to P<0.01).Conclusions:With the change of the phase in menstrual cycle,the levels of E₂ and P,and breast structure change.The breast tenderness is related to the levels of E₂ and P,and the ADC value is closely related to the levels of E₂ and P in different menstrual cycle.