For many long centuries, the function of the human cardiovascular system was an important issue among scholars of different eras and areas. Abubakr Muhammad ibn Zakariyya al-Razi (865-925 AD), known by the Latin name Rhazes, was one of the scholars concerned with this issue. This physician is recognized as the first great scientist of the Golden Age of Islamic Medicine (9th-12th centuries AD). He authored Kitab al-Mansuri (Liber Al-Mansuri), a ten-volume medical encyclopedia that covers a large number of medical subjects. The first chapter of this book is allocated to human anatomy and functions. In this article, we review the chapter from Al-Mansuri that deals with Rhazes' views on the cardiovascular system.