1. Objective To investigate characteristics of menstrual patterns according to Sasang Constitutional disease, and to utilize for diagnosis and treatment of Sasang Constitutional disease. 2. Method The recruited subjects were 430 women who convinced their Sasang Constitution by taking herbal medicine and improving of chief complaint. The items of data contain age at menarche, age at menopause, menstrual cycle, menstrual duration, cyclic regularity of menstruation, severity of menstrual pain, the worst day of menstrual pain, type of menstrual pain, amount of menstruation. 3. Results 1) Severity of menstrual pain, the worst day of menstrual pain, menstrual pain accompanied with nausea were significant among Sasang Constitutional diseases. 2) In Bae-chu-pyo-byeong disease (背椎表病證), Wi-wan-han disease (胃院寒證), So-eum disease (少陰證) and Tae-eum disease (太陰證), menstrual pain was severer than other diseases. 3) In Hae-yeok disease and So-yang-sang-pung disease (少陽傷風證), the worst day of menstrual pain was a day before menstruation. In Hyung-gyeok-yeol disease (胸膈熱證), Tae-eum disease (太陰證), So-eum disease (少陰證), the frequency of a day after menstruation in the worst day of menstrual pain was higher than other diseases. In Wi-wan-han disease (胃院寒證), Mang-yang disease (亡陽證), the frequency of two day after menstruation in the worst day of menstrual pain was higher than other diseases. 4) In So-yang-sang-pung disease (少陽傷風證), Mang-eum disease (亡陰證), Eum-heo-o-yeol diasese (陰虛午熱證), Ul-gwang disease (鬱狂證), Tae-eum disease (太陰證), So-eum disease (少陰證), the frequency of menstrual pain accompanied with nausea were higher than other diseases. 4. Conclusion Menstrual patterns, especially menstrual pain is different among Sasang Constitutional diseases. Assessing menstrual pain can be used for diagnosing Sasang Constitutional diseases, deciding treatment course, determinating prognosis.