Small cell carcinoma and small portions of poorly differentiated adenocarcinoma of the stomach sometimes differentiate into secretory cells. We experienced a pure endocrine carcinoma of the stomach. The patient, who had a giant mass in the greater curvature of the body of the stomach and regional lymph node metastasis, underwent total gastrectomy. Immunohistologic staining of the resected specimens revealed that the tumor was an endocrine carcinoma. The tumor cell shape in the present case was polygonal or oval and the cell size was relatively large. The cell nucleus was coarse chromatic and nucleoli were seen, whereas, the nucleus of small cell carcinoma often shows a fine chromatic pattern and nucleoli are not seen. On the basis of these findings, the present case was considered to be a pure endocrine carcinoma which was not classified as a small cell carcinoma.