The aim of this study was to investigate the relationship between several menstrual characteristics and Yin-Yang, using the traditional Korean Sasang typology in 565 female college students. Using the questionnaire for the Sasang Constitution Classification, which consists of 121 forced-choice items, subjects were classified into three groups: So-Yang (small Yang, n=194), Tae-Eum (large Yin, n=164) and So-Eum (small Yin, n=207). Tae-Eum-type subjects showed significantly higher body mass index (BMI) values than other types. There was also a significant difference in menstrual duration between the Tae-Eum and So-Eum groups. However, there were no differences in the cycle or pattern of menstruation, or in the amount of menstrual blood among the groups. There were also no significant differences in the menstrual variables between Yin and Yang subjects. In conclusion, our results regarding the relationship between menstrual cycle and Yin-Yang types are inconsistent with traditional theory. However, this study shows that menstrual duration and BMI differ significantly among Sasang types.