The expression of the cytokeratins (CK) 1, 5, 6, 7, 10, 13 and 14 was studied immunohistochemically in gastric biopsies from both the antrum and the body of 70 patients. Normal gastric foveolar epithelium (9 cases) Helicobacter pylori gastritis (23) and intestinal metaplasia (38) were examined. Positive staining results for CK 1, 5, 10 and 14 were not observed using the 34 beta E12 antibody. With antibodies to CK 5/6, 7 and 13 some, but not all cases, were immunoreactive. Predominantly positive staining included less than 10% of the cells and was always restricted to the tips and the juxtaluminal areas of the foveolae. No difference was seen between the antrum and the body. Comparing normal gastric mucosa with gastritis and intestinal metaplasia, cases positive for CK 5/6 were observed less frequently in intestinal metaplasia types II and II compared to the other groups. CK 7 was expressed exclusively in intestinal metaplasia. CK 13 was seen in all groups of specimens. Thus, cytokeratins typical for ductal structures (CK 7) and squamous epithelia (CK 5/6, CK 13) can be regarded as an inconstant, but not unusual observation in the gastric mucosa. Their expression may be controlled by both differentiation-related as well as environmental factors.