With Ibn Sina great Canon came the golden age of Arabic medicine, almost to its peak. Since the beginning of XI century, when Ibn Sina died, until the middle of XIII century, when creative was Ibn al-Nafis, medical science continues to develop and progress, and had its brilliant minds. For that time characteristic is the fact that neither the strong authority as Avicenna was could paralyze the progress of medical science. Three hundred years before Paracelsus, in Cairo appears a medical scientist who dares to touch the authority of Ibn Sina-Avicenna in the infallibility of CanonMedical Bible. The scholar was called Alauddin Ibn al-Nafis (1210-1288). He, 250 years ago Servet, (Michael Servetus, XVI century) reveals the truly describes the small or pulmonary circulation, but also gives a description of the great forerunner of the bloodstream. In his separate work on the anatomy, Ibn al-Nafis in five places contested arguments of Galens teachings, which also Ibn Sina was accepted. He very persuasively argues that the blood does not oxidize (does not mix with air ), passing through some hypothetical pores in the partition between the right half of the heart, in which blood is collected and left half, in which, supposedly is the air, but that this happen when the blood is going from the right ventricle through the pulmonary artery into the lungs, where it is mixed with air and thus converted murmurs through the pulmonary vein into the left half of the heart. On occasion of the 800th anniversary of Ibn al-Nafis birth, one of the largest Arab and world doctors of all times we publish this article so that readers get something closer image his creative work, especially the one which relates to his contribution to the discovery of cardiac and pulmonary circulation, revolutionary discoveries in the world of medicine. In the year 1924 a heated debate started regarding the discovery of the pulmonary circulation. This discovery was attributed only to European scholars. It stemmed back to the sixteenth century. When Michael Servetus (1511-1553), Anderea Vesalius (?1514-1654), Nicolai Massa (1485-1569), Realdo Colombo (1520-1654), Valverde De Hamusco (1508-1565), Andera Cesalpino (1519-1603), Fabrici dAquapendent (1533-1619) and William Harvey (1578-1657) developed the concept. However, Muhyi-d-din At-Tatawi (1896-1945) presented his thesis Der Lungenkreislauf nach El-Korachi. Dissert, z.eil. d. Doktorwrde, Freiburg im Brisgau 1924 of the blood circulation according to al Qurashi relaying on his discovery of his description of pulmonary circulation in one of ancient manuscripts, He proposed that the real credit for the discovery of the pulmonary circulation belongs this eminent physician of the thirteenth century: Ibn al-Nafis. Later another doctor Abdul Kareem Chihade (1922- ) presented another dissertation in Paris 1951 entitled decouverte de la circulatio pulmonaire chez Ibn an-Nafis. Published by Institut Francais De Damas 1955. Other promin
Key words: Ibn al-Nafis, cardiac circulation, pulmonary circulation.