Small cell carcinomas most often arise in the lung, and metastatic involvement of the stomach is uncommonly reported. Primary small cell carcinomas of the stomach have similar biological features to those of pulmonary small cell carcinomas, an aggressive behavior, with a very poor prognosis. Herein, two cases of primary gastric small cell carcinoma, diagnosed after gastrectomy from their clinicopathological features, are reported. A 78-year-old female and a 68-year-old male with dyspepsia and weight loss, respectively, were admitted to our hospital. Their upper gastrointestinal endoscopy and abdomen-pelvis CT were checked. A preoperative histological examination of the endoscopic biopsy specimens revealed poorly differentiated adenocarcinomas. A radical subtotal gastrectomy was performed for both patients. The histological finding and immunohistochemical staining of the resected stomach indicated small cell carcinomas. After the operations, the patients were discharged without any postoperative complications. Postoperative adjuvant chemotherapy, with cisplatin and etoposide, was performed for the latter patient. The patients have been followed up for 10 and 8 months, respectively, without recurrence or metastasis.