[Keeping an eye on Brazil: medical geography and Alphonse Rendu's journey]

This article emphasizes the important role Natural History has played in the production of medical knowledge from the end of the eighteenth century on. It also tries to clarify the strategic position Brazilian empire came to have in the nineteenth century in relation with etiologically and environmentally oriented research programs under the patronage of Medical Geography. The analysis of the French physician Alphonse Rendu's travel reports, from 1844 to 1845, leads to the recognition of a very specific period of that branch of European medical schools. Besides, the article provides the recognition of a second period of Medical Geography, that starts with the creation of th Archives de Médecine Navale in the 1860's.