Bartolomeo Eustachi (c. 1500–1510 – 27 August 1574), also known as Eustachio or by his Latin name of Bartholomaeus Eustachius (/juːˈsteɪʃəs/), was an Italian anatomist and one of the founders of the science of human anatomy.

Bartolomeo received the required broad humanistic education typical of that time, and then studied medicine at the Archiginnasio della Sapienza in Rome.

[2] Eustachius was deeply interested in understanding the anatomical structures of the human body through direct observation, instead of accepting the many a priori theories current among other physicians.

Trying to understand how diseases affected body structures, Eustachius made comparative anatomical analysis of healthy and disease-altered organs (pathological anatomy).

These were completed in 1552, nine years after Vesalius had published his magnum opus, De Humani Corporis Fabrica Libri Septem in Basel.

Published in 1714 by Giovanni Maria Lancisi at the expense of Pope Clement XI, and again in 1744 by Cajetan Petrioli, and again in 1744 by Bernhard Siegfried Albinus, and subsequently at Bonn in 1790, the engravings show that Eustachius had dissected with the greatest care and diligence, and had taken the utmost pains to give accurate views of the shape, size, and relative position of the organs of the human body.