In the Amazon frontier, as well as in other regions of Brazil, illnesses' risks are similar. Dengue, parasitic diseases, cancer and cardiovascular diseases are common here and there. A reality significantly different from that faced in the period of colonization: malaria, respiratory diseases, accidents, violence, etc. The migrants' discourses are loaded with memories and representations of events of these risk situations. Studying these trajectories and memories allows us to understand the potential of the community to adapt to shocks and modify reality. This was the aim of this study. We conducted nine semi-structured interviews with pioneers of colonization and four focus groups with 24 health professionals from the municipalities of Alta Floresta, Carlinda and Paranaíta, State of Mato Grosso, Brazil. Each focus group built a timeline, which was used as a tool to discuss environmental-health relationships over six phases that define the region's colonization and development: deforestation, mining, family farming, ranching, timber extraction, environmental supervision and construction of dams. The generative themes that triggered debate were: diseases, health, environment, socioeconomic conditions and lifestyles. A set of multiple and dynamic factors appear as a determinant of health problems. On one hand, they have their origin in the ecosystem (agents and vectors of malaria) and human action on it: deforestation (accidents) and forest burnings (respiratory diseases). On the other, they derive from socioeconomic factors: conflicts over land and gold (violence) and poverty (parasitic diseases and infant mortality). In both cases, the intensity of migration, lack of preventive information and shortcomings of health and safety, exacerbated illness risk. The end of the malaria epidemic (2006) was associated with the closure of mines (1992), the intensification of health services (1990s) and control of deforestation (2000s). The latter also had an impact on the occurr