Earlier studies of the natural history of Chagas disease (ChD), which is caused by the protozoan Trypanosoma cruzi , had suggested that the consequences of the disease in the elderly are negligible. The objective of this study was to estimate long-term mortality in ChD in old age using data from a large population-based cohort study. The study was conducted in Bambui City (~15,000 inhabitants), Brazil. Participants were 1479 residents aged 60 years and over (84.9% from total), who were followed from 1997 to 2007. During a mean follow-up of 8.72 years, 567 participants died, resulting in a total of 12,896 person-years observation. The baseline prevalence of T. cruzi infection was 38.1%. T. cruzi infection was a strong predictor of mortality among cohort members, and this association remained largely significant after adjustments for age, sex, and conventional cardiovascular risk factors (hazard ratio [HR] = 1.56; 95% CI 1.32–1.85). Increased risks for mortality associated with T. cruzi infection were consistently observed in those aged 60–69 (HR= 1.79; 95%CI 1.37–1.85), 70–79 (HR=1.35; 95% CI 1.04–1.76) and 80 years and over (HR= 1.59; 95% CI 1.09–2.33). Overall, population attributable risk for mortality due to T. cruzi infection was 13.2% (95% CI 9.8–16.4). Our results indicate that ChD is a relevant individual and population health issue in old age, supporting the need for measures to reduce the burden of ChD in this growing segment of the population.