Ibn Al-Nafees worked in the hospital as a physician, and later as a teacher of medicine. Owing to his studious nature and excellence in medicine, he became head of the Hospital and manager of its Medical school. Some years later, he moved to work as head of the Mansoori Hospital which was established by Sultan Al-Mansoor Ibn Qalawoon in 680 A.H. (1281 A.C.). Ibn Al-Nafees occupied several positions until he became the physician of Sultan Al-Dhahir Beibers. The article, Ibn Al-Nafees and Discovery of the Blood Circulation System, gives us a brief account on the life of this great Muslim scientist.