One hundred and twenty-one patients with gastric cancer of Borrman IV (type 4) were classified into two types according to the macroscopic appearance of their tumors, namely, those tumors with giant folds (type G, n = 84) and those without giant folds (type P, n = 37). A large percentage of the cases in both type groups had advanced stage carcinoma. Type G was found to be predominant in young women and the incidence of high-grade lymph node metastasis was higher in type G than in type P. Histochemically, it was shown that the tumor interstitium of type G contained obviously many more acid mucopolysaccharides (AMPS) than the localized Borrman II (type 2) gastric cancer, which was used as a control. The results of enzymatic digestion tests suggested that the amounts of hyaluronic acid, chondroitin sulfate, and sialic acid were greater in type G than in type P or the localized type, the differences involved being marked between type G and the localized type.