Immunolocalization of a variety of integrins using monoclonal antibodies against beta 3, beta 5, alpha 3 beta 1 and alpha 6, and polyclonal antibodies against vitronectin receptor (alpha v beta 3) and beta 1 were investigated on PLP-fixed paraffin sections of 19 cases of advanced gastric carcinomas. The beta 5 integrin, which pairs only with the alpha v subunit, was positive in seven cases (37%), and was associated closely with scirrhous invasion (P < 0.05). beta 5 was positive chiefly in the cytoplasm of carcinoma cells and infrequently in cell membranes. beta 3, which is another subunit pairing with alpha v, was positive in six cases (32%), and tended to be associated with scirrhous invasion (P < 0.01). beta 3 was also located chiefly in the cytoplasm. Five of the seven beta 5-positive cases showed coexpression of beta 3. Polyclonal antibodies to alpha v beta 3 also showed a significant difference among the amounts of stroma (P < 0.05). Anti-beta 1 antibodies showed clear positivity in many cases (89%). Of the beta 1 integrins, alpha 3 beta 1 was positive in a few cases (26%) without any preferential pattern, and laminin receptor subunit alpha 6 stained on cell membranes of neoplastic epithelia in many cases of carcinoma (89%) except for mucinous carcinoma These distinctive patterns of integrin positivity indicate a close association of beta 5 and beta 3 expression with scirrhous invasion in gastric carcinoma.