Immunohistochemical localization for carbohydrate antigen 19-9 (CA19-9) was studied in the gastric tissues from 115 patients with advanced gastric carcinoma. We compared two groups: 57 patients who died of recurrence or metastases within 2 yr (group I) and 58 patients who survived 5 yr or more after resection (group II). The staining patterns were classified into negative, apical, and/or cytoplasmic type and stromal type. Thirty-three cases (58%) of group I showed a stromal type, whereas only 17 cases (30%) of group II showed the same type. In undifferentiated type carcinoma, the stromal type was seen in 20 cases (65%) of group I and seven cases (23%) of group II. However, in differentiated type carcinoma, there was only a small difference in the appearance of stromal type between group I (50%) and group II (37%). The immunohistochemical localization for CA19-9 in the tumor tissues, particularly in undifferentiated carcinoma, will be useful in predicting the prognosis of the patients with advanced gastric carcinoma.