SUMMARY The purpose of this study was to determine the magnitude and distribution of acute gastrointestinal illness (GI) in the Chilean population, describe its burden and presentation, identify risk factors associated with GI and assess the differences between a 7-day, 15-day and a 30-day recall period in the population-based burden of illness study design. Face-to-face surveys were conducted on 6047 randomly selected residents in the Metropolitan region, Chile (average response rate 75·8%) in 2008. The age-adjusted monthly prevalence of GI was 9·2%. The 7-day recall period provided annual incidence rate estimates about 2·2 times those of the 30-day recall period. Age, occupation, healthcare system, sewer system, antibiotic use and cat ownership were all found to be significant predictors for being a case. This study expands on the discussion of recall bias in retrospective population studies and reports the first population-based burden and distribution of GI estimates in Chile.