The article is dedicated to the 350 th anniversary of the death of the Dutch anatomist, physiologist, yatrochemist and the greatest physician of the XVII century, Franciscus Sylvius (Franz de le Boe) (1614-1672). His contribution to the study of the structure of the nervous system is characterized, as well as the main scientific discoveries and achievements in building a rational system of medical science and practice. It is stated that eponym «aquaeductus Sylvii» was coined by Lorenz Heister in 1717 in his paper «De admiranda cerebelli structura».