We report a 73-yr-old man with primary advanced gastric small cell carcinoma, pure type. A large, Borrman type I tumor was located from the cardia to the entire gastric fundus and upper body. Atypical cells showed a round nucleus, small nucleolus, dense to granular chromatin, and scant cytoplasm. The histological findings indicates an advanced stage and exposure to the gastric serosa. Mitotic figures were observed. There was a proliferation of a sheet-like, solid pattern, but no rosette-like, sqamoid, or glandular patterns. The neoplastic cells were positive for Leu-7 (CD57) and 123C3 (CD56, neural cell adhesion molecule, NCAM) on the surface membrane. We diagnosed this case as primary advanced gastric small cell carcinoma, pure type, and report that Leu-7 and 123C3 monoclonal antibodies are useful markers for gastric small cell carcinoma. The 32 previously reported cases of gastric small cell carcinoma are also reviewed.