Background parenchymal enhancement (BPE) on breast contrast MRI is known to be associated with the menstrual cycle. We conducted a multicenter study to evaluate the effect of the menstrual cycle on BPE and cancer detectability by contrast-enhanced breast MRI in an Asian population. The Degrees of BPE and cancer detectability were assessed quantitatively and qualitatively. BPE were strongest in the proliferative phase. The detectability of breast cancer was better at the menstrual and proliferative phases than at secretary phase. Not only the proliferative phase but also the menstrual phase is suitable for breast MRI examinations of premenopausal Asian women.