Background: This study assessed the prevalence of gastroesophageal reflux disease (GERD) in a general adult population from Temuco in southern Chile. The association of GERD with demographic variables was also examined. Methods: A cross-sectional study among the general population of Temuco in southern Chile was conducted in 2017, using a validated and reliable questionnaire for detecting GERD. The urban area of Temuco, with a population of 245,317 inhabitants (2002 census), was divided into four zones, which were representative of the socioeconomic sectors of the city. The sample size was estimated assuming a prevalence of 52.8%, an accuracy of 3.0%, a confidence level of 95.0%, and a design effect of 1.15. Area sampling was used to build clusters. The prevalence of GERD was determined and associated factors were studied by means of bivariate and multivariate analyses. Results: A total of 1,069 subjects (47.9% women, median age 40 years) from the selected subareas were interviewed. The prevalence of GERD was 44.8%. The most frequently reported symptom was regurgitation (54.8%). One-third of subjects took medication to control symptoms and was considered 'sick' by the instrument, although >68% of them had never sought medical consultation. There was a significant association between GERD and age (P < 0.001) and female gender (P = 0.001). Conclusions: In this population-based study, the prevalence of GERD was high (44.8%). GERD was associated with age and female gender.