Chronic Non-Communicable Diseases are the main source of disease burden in Brazil. In 2011, the Brazilian Ministry of Health launched the Strategic Plan of Action for Management of Chronic Non-Communicable Diseases focusing on population-based interventions to manage cardiovascular diseases, diabetes, cancer, and chronic respiratory diseases mainly through fighting tobacco use, unhealthy diets, physical inactivity and the harmful use of alcohol. Although a significant number of scientific studies on chronic diseases and their risk factors have been undertaken in Brazil, few are of cohort design. In this context, the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil), a cohort study of 15,105 Brazilian public servants reflects the reality of high prevalences of diabetes, hypertension and the main chronic diseases risk factors. The diversity of information that the Study will produce can provide important input to better understand the causes of chronic diseases and to support public policies for fighting them.