The histochemical patterns of mucosubstances in 1.010 intestinal metaplasia (IM) foci in stomachs removed during surgery for benign ulcer and carcinoma has been studied. Two kinds of IM were characterized: the complete and the incomplete types, with the first one subdivided in Small intestine Type I, Small intestine Type II, and Colonic type, based on their similarity of mucosubstances, with those found in normal small intestine and colon, and the second one divided in two groups, depending on the presence or absence of sulfomucins. The incomplete type with sulfomucins was significantly more frequent in patients with carcinoma than in benign ulcer cases (P less than 0.001) as well as, in stomachs bearing intestinal type of carcinoma than in stomachs with diffuse type of carcinoma (P less than 0.005). The significance of the different types of IM, in relation to the gastric pathologic findings is discussed.