By combining two of the morphological characteristics of gastric cancer, the degree of differentiation of the glandular tubules and the amount of mucus in the cytoplasm, the histological type of the gastric carcinoma was categorised into four groups. Group I: tubular differentiation--well; mucus in cytoplasm--poor; group II: tubular differentiation--well; mucus in cytoplasm--rich; group III: tubular differentiation--poor; mucus in cytoplasm--poor; group IV: tubular differentiation--poor; mucus in cytoplasm--rich. A study of the relation between the types of primary lesion and the mode of extension and recurrence of gastric carcinoma in 200 autopsy cases was then undertaken. In group I, the frequency and extent of haematogenous metastasis such as in the liver was high, while in group IV, that of lymph node metastasis, direct invasion into surrounding organ, and peritoneal dissemination were higher. In group III, which showed the intermediate mode of extension in nature to those of group I and IV, although the frequency and severity of the bone marrow metastasis was the highest. There were significant differences in the modes of development and the extent of infiltration in all groups.