This article is an analysis of the performance of the Rockefeller Foundation in the development of the cientific, sanitary, and medical services in Brazil, in the period that goes from 1915, with the first contact with Brazilian politicians, up to the beginning of the 1920' s, that determined the consolidation of an important stage of Sanitary Reform in Brazil. By discussing one of the most relevant periods of this North American foundation performance in the country, this work tries to emphasize the importance of the subject to the historian. In this sense, we cannot understand the formation of the medical carreer in Brazil without taking into account the creation of cientific carreers directed to the teaching, and research in the biomedical area by the Rockefeller Foundation. We cannot understand the origins of health carreers in the country without considering ais o to the contribution of the Rockefeller foundation to the development of sanitary campaigns in national scale, and in the request for sanitarists of strong cientlfic forination. The origins of the medical and sanitarist profissionalization are strongly linked to the work of the Rockefeller Foundation in Brazil.