[Domingos José Freire and the beginnings of bacteriology in Brazil].

The article examines the trajectory of Domingos José Freire, a bacteriologist who attained great national and international renown in the final quarter of the last century for claiming to have discovered the yellow-fever microbe and a vaccine that was administered to thousands of people. The article reviews the main controversies protagonized by this scientist and endeavors to show the role be played in the enthronement of Pasteurian medicine in Brazil.