The present research seeks to analyze the process of conformity of the hygienist medical knowledge as a knowledge able to educate the child, being the same in the core of the elaboration of the education project of the first decades of the republican regime. We are interested in understanding how this knowledge was gaining corporeity within the city of Natal / RN, legitimizing itself as a knowledge able to forge a new man - educated, orderly, free of addictions and fit for work. Such a human ideal was in direct dialogue with the aspirations of the local intellectual elite who traced in the urban scene the paths to be followed to reach the same degree of civility and development of the countries considered symbols of a positive and scientific modernity. In this project, the child had been taken as the focus of varied interventions, which acted in their lives from the public space of the street, to the privacy of homes, from the idealization of an identity that had in physical and mental plasticity, its main characteristic, which made the child an individual prone to transformation. The choice for a local setting tried to make possible the understanding of the specificities of an educational project of its own, but also to dialogue with other larger realities to a greater or lesser extent. As a research demarcation, we adopted the creation of the Public Hygiene Inspectorate as the initial landmark (1892), since this institution constituted itself as normative space of medical practice, gaining legitimacy to intervene in broad aspects of social life. The final landmark coincides with the publication of the book Inspecção Médico-Escolar of Dr. Alfredo Lyra. Published in 1922, the work sought to provide scientific basis for sanitary inspections in schools subsidized by the state, especially the School Groups. These inspections were responsible for constructing for each school a detailed inventory of the health conditions - physical and mental - of the students from Rio Grande do Norte, as well as acting as criteria ...