Physicians took part in the promotion of public policies that regulated urban and architectural work, before engineers, architects, planners, and even before the State had a chance to take part in the formulation of such policies. Starting in the late nineteenth century, and especially during the first decade of the twentieth century, the State began to lead on the issue of hygiene and public health. This paper focuses on the role of these professionals, who generated debates within their respective disciplines, or provided –as ministries, public servants or consultants- technical knowledge to the central government. These debates are still relevant for two reasons. First, they serve as reminders of the way in which the voice of these professionals was crucial not only within their respective disciplines, but also in order to place the issue of hygiene and public health on the agenda and to promote public policies related to the urban environment and its population. Secondly, these debates represent a challenge to current planners, as this historic context provides insight on the complex relationship between public health and planning, which hitherto has received little attention.Physicians took part in the promotion of public policies that regulated urban and architectural work, before engineers, architects, planners, and even before the State had a chance to take part in the formulation of such policies. Starting in the late nineteenth century, and especially during the first decade of the twentieth century, the State began to lead on the issue of hygiene and public health. This paper focuses on the role of these professionals, who generated debates within their respective disciplines, or provided –as ministries, public servants or consultants- technical knowledge to the central government. These debates are still relevant for two reasons. First, they serve as reminders of the way in which the voice of these professionals was crucial not only within their respective disciplines, but also in order to place the issue of hygiene and public health on the agenda and to promote public policies related to the urban environment and its population. Secondly, these debates represent a challenge to current planners, as this historic context provides insight on the complex relationship between public health and planning, which hitherto has received little attention.