Gastric mucosa of 585 patients at risk for gastric carcinoma and undergoing oesophago-gastroscopy for dyspeptic symptoms was examined histologically and histochemically. Sixteen (2.7%) of the patients studied showed gastric carcinoma. The intestinal type of gastric carcinoma was the most common, present in males over 40 yrs old, and was found in 1:16. Early cancers were present in 3 patients. Chronic atrophic gastritis of the A, B and AB types was present in 32.8%. Types A and AB were noted sporadically. Males over 40 and tobacco smokers showed the prevalence of the type B (idiopathic chronic pangastritis) and incomplete intestinal metaplasia. No relationship of the mucosal precursor lesions to sulpho- and sialomucins were detected. Helicobacter pylori infestation of gastric mucosa was present in 81% of patients and relatively common in the young patients with normal gastric mucosa; therefore this finding confirms a predilection of Helicobacter pylori to the Third World.