This paper discusses the ideas of ming-men (the gate of life) in traditional Chinese medicine during the Chin, Yuan, and Ming periods (1127-1644). Although physicians held various opinions about ming- men's position, nature, and relationship with other visceral systems and circulation trucks in the body, they unanimously viewed ming-men as the most important part of the body and the key of life. Upon their discussions, this paper explores how traditional Chinese physicians understood the formation and development of human embryos as well as the different structure of body in terms of gender. Questions as to why physicians were highly interested in ming-men and the relationship between medicine, Confucianism, Taoism, and Buddhism will also be discussed.