Background:One-third of adults worldwide are physically inactive causing over 5.3 million deaths annually. Despite a growing focus on physical activity and health, population-based data on physical activity trends in low- and middle-income countries are still limited. To help fill the gap, this study provides trend data over a 10-year period in Pelotas, a southern Brazilian city.Methods:The short version of the International Physical Activity Questionnaire was used to assess the prevalence of physical inactivity in 2002 (n = 3119), 2007 (n = 2969), and 2012 (n = 2868). Levels of inactivity and trends were assessed according to sex, age, schooling, and socioeconomic position (SEP).Results:The prevalence of physical inactivity rose from 41.1% (95% CI: 37.4–44.9) in 2002 and 52.0% (95% CI: 49.1–53.8) in 2007 to 54.4% (95% CI: 51.8–56.9) in 2012 (P < .001). Physical inactivity significantly increased in all subgroups except in the highest SEP and 70+ year age subgroups.Conclusions:After a sharp increase in the prevalence of physical inactivity from 2002–2007, levels plateaued from 2007–2012. However, it is important to stress that current levels are still unacceptably high, and that efforts must be intensified to reverse the trend.