Aim: To determine the prevalence of peptic ulcer and gastric adenocarcinoma in a population of middle and high socio-economic status in Lima, Peru, between 1985 and 2002. Materials and methods: The prevalence of gastroduodenal ulcer and gastric adenocarcinoma was determined after studying by esophagogastroduodenoscopy 31,446 patients at the Policlínico Peruano Japonés (PPJ) between 1985 and 2002. All patients had chronic upper gastrointestinal symptoms and had endoscopically proven diagnosis of active peptic ulcer or histological diagnosis of gastric adenocarcinoma. Results: Analysis of PPJ population identified a decrease in the prevalence of gastric ulcer and duodenal ulcer from 3.15% and 5.05% respectively in 1985, to 1.62% and 2.00% respectively in 2002. Gastric adenocarcinoma prevalence also decreased from 3.19% in 1988 to 0.92% in 2002. The prevalences of gastric ulcer (OR=1.49, 95% IC 1.26-1.77, p<0.001), duodenal ulcer (OR=1.32, 95% IC 1.15-1.51, p<0.001) and gastric adenocarcinoma (OR=1.53, 95% IC 1.25-1.86, p<0.001), decreased in the last eight years. Conclusions: Over the study period, there was a significant decrease in the prevalence of peptic ulcer and gastric adenocarcinoma at the Policlínico Peruano Japonés, where patients from middle and high socio economic status are attended.