Introduction: Chronic gastritis is one of the most common diseases in the population. Several factors influence its appearance; however, the effect of high altitude has not been studied thoroughly. Objective: To determine the association between the altitude of the residential area and chronic gastritis in outpatients of Peru. Methods: Observational, analytical, and cross-sectional study. Secondary data analysis was conducted. The dependent variable was chronic gastritis, obtained from patient references, and verified in the medical history according to the pathological history mentioned during medical consultation. The independent variable was the altitude of the residential areas (categorized into low altitude, intermediate altitude, high and very high), and the secondary co-variables were age, sex, and time living at altitude. Generalized linear models were used to estimate prevalence ratios using Poisson family and city as a cluster. Results: Of the 4263 patients studied, 63% were female; the median age was 42 years. The overall prevalence of chronic gastritis was 12,9%. There was an association with chronic gastritis and altitude of residence at the intermediate and high levels, but not at the very high; with an adjusted prevalence ratio of 1.52 (95% confidence interval, 1.03 to 2.23); 2.01 (1.55 to 2.60) and 1.12 (0.84 to 1.48), respectively. Conclusions: We found a significant association between chronic gastritis and intermediate and high altitude but not at very high, which could be explained by hypobaric hypoxia in altitude that could lead to gastric wall lesions and other socio-demographic variables.