Venous valves are delicate structures, the integrity of which is crucial for the normal function of the venous system. Their abnormalities lead to widespread disorders, ranging from chronic venous insufficiency to life-threatening thromboembolic phenomena. The discovery of the venous valves, however, has been the subject of hot controversy. Even though Fabricius ab Aquapendente is credited with the discovery by most historians, we demonstrate in this paper that other anatomists described them many years before Fabricius ab Aquapendente publicly demonstrated them in Padua in 1579. A thorough review of the historical literature surrounding the discovery of the venous valves was carried out from 1545 to the present under the supervision of the Medical History Department of our institution. Research was performed at the History of Medicine Division of the National Library of Medicine and through MEDLINE access to the medical literature. The Parisian Charles Estienne first mentioned the venous valves in his 1545 publication when he described "apophyses membranarum" in the veins of the liver. Lusitanus and Canano publicly demonstrated them in the azygos vein during cadaver dissections performed in Ferrera, Italy. The Parisian Jacques Sylvius described valves in the veins of the extremities in 1555. The work of these anatomists, however, could not achieve full recognition, because Andreas Vesalius, the leading anatomist at that time, was unable to confirm their findings and strongly denied the existence of venous valves. Vesalius's influence was so powerful that research on the subject was idle until 1579, when Fabricius ab Aquapendente "discovered" the venous valves. About the same time, the German Salomon Alberti published the first drawings of a venous valve (in 1585). William Harvey, a disciple of Fabricius ab Aquapendente, finally postulated the function of the venous valves, providing anatomical support for one of the greatest discoveries in medicine: the blood circulation. Therefore, our investigations revealed that Estienne and Canano discovered the venous valves in the 1530s. Fabricius ab Aquapendente's achievement was their full recognition 64 years later. However, it was not until 1628 that their function was fully understood, with the discovery of the blood circulation by William Harvey.