Primary gastric choriocarcinoma is a highly malignant and very rare tumor. A 44-year-old man was referred to our hospital, with a diagnosis of gastric adenocarcinoma made by histologic examination of the endoscopic biopsies in an other medical center. The patient underwent total gastrectomy and omentectomy. Histological examination of the gastrectomy specimen revealed gastric choriocarcinoma. Postoperative chemoteraphy was performed and the patient died of disease 4 months after operation.