INTRODUCTION AND AIM: The gastric mucosa has been studied since the pre-Helicobacter pylori (H. pylori) era, but the complete descriptions of the stomach and duodenum have been anecdotal, and those of the distal duodenum, exceptional. Our aim was to evaluate the different epidemiologic characteristics and the gastroduodenal inflammatory status in patients with upper gastrointestinal symptoms. MATERIALS AND METHODS: We studied 138 patients divided into: the non-ulcer group (functional dyspepsia [n = 77] and GERD [n = 27]) and the ulcer group (peptic ulcer [n = 13] and duodenal ulcer [n = 21]). Ten biopsy samples (2 from the corpus, 3 from the antrum, 3 from the proximal duodenum, and 2 from the distal duodenum) were taken in each patient for histologic and/or microbiologic study. RESULTS: The prevalence of dyspepsia, functional dyspepsia, and H. pylori was 80.4%, 69.4%, and 82.6%, respectively. The frequency of superficial chronic gastritis in the corpus was significantly higher in the ulcer group vs. the non-ulcer group, whereas there was more chronic atrophic gastritis in the antrum in the ulcer group (P < 0.05). Duodenitis was significantly more frequent in the ulcer group vs. the non-ulcer group, in both the proximal and distal duodenum. Pangastroduodenitis was a significant finding in the ulcer group. In both groups, chronic gastritis (corpus and antrum) and duodenitis (proximal and distal) were significantly related to the presence of H. pylori. Proximal duodenitis is not an uncommon finding in functional dyspepsia (37.7%) and is twice as frequent as distal duodenitis (16.9%). CONCLUSIONS: The ulcer group presented with a gastroduodenal inflammatory map different from that of the non-ulcer group and was characterized by a higher frequency of superficial chronic gastritis in the corpus, chronic atrophic gastritis in the antrum, and a very high frequency of proximal duodenitis.