A 55 year-old man was admitted with epigastric pain of one-month duration. We performed an esophagogastroduodenoscopy that showed the presence of a 3 cm sized polypoid mass at the lesser curvature side of the antrum. A biopsy demonstrated the presence of a neuroendocrine carcinoma of the stomach. A subtotal gastrectomy with D2 lymph node dissection was performed and the microscopic features of the resected specimen confirmed the diagnosis of a composite large cell neuroendocrine carcinoma with an adenocarcinoma of the stomach. A gastric neuroendocrine carcinoma is extremely rare and a composite neuroendocrine carcinoma with an adenocarcinoma of the stomach has been rarely reported. We report a case of a gastric composite tumor with an adenocarcinoma and a large cell neuroendocrine carcinoma.