This study was performed to investigate the relationship between CD44 expression and depth of, tumor invasion histopathologic differentiation, tumor size, lymph node metastasis, and proliferating capacity of tumor cells in the gastric carcinoma. In 20 cases of early gastric carcinoma (EGC) and 40 cases of advanced gastric carcinoma (AGC), the immunohistochemical staining for CD44v3, CD44v5, and PCNA gave the following results. 1) In all 60 cases, the positive rates for CD44v3 and CD44v5 were 18.3% and 71.7%, respectively. 2) CD44v5 was expressed in 45% of EGC and 85% of AGC. 3) Larger tumors exhibited higher positive rates for CD44v5. 4) There were 28 cases of lymph node metastases out of 43 cases of CD44v5- positive primary gastric carcinomas (65.1%), and there were 4 cases of lymph node metastases out of 17 CD44v5-negative cases (23.5%). 5) There was no relationship between CD44v5 expression and PCNA index. Because the tumors that exhibit deep invasion, and large in size and have lymph node metastses tend to have more frequent expression of CD44v5, CD44v5 may be one of the useful prognostic markers for gastric carcinoma.