A primary gastric choriocarcinoma (PGC) is a rare tumor, with only approximately 140 cases reported in the international medical literature. A choriocarcinoma is a rapidly invasive, widely metastatic, human chorionic gonadotropin (HCG)-producing neoplasm, which is usually intrauterine and gestational, the pathogenesis of which is still uncertain. Herein, the case of primary gastric choriocarcinoma, associated with an adenocarcinoma in a 72-year old man, who presented with gastrointestinal bleeding and a gastric mass, clinically suspicious of a gastric adenocarcinoma, with GB and CBD stones, is reported. Thus, a radical subtotal gastrectomy and lymph node dissection, with reconstruction, and a cholecystectomy, with choledocholithomy T tube insertion, were performed. The resected specimen was found to be a Borrmann type I tumor, and a histological examination revealed this to be a primary gastric choriocarcinoma, associated with an adenocarcinoma and a syncytiotrophoblast, which was immunostained using human chorionic gonadotropin (HCG). The serum HCG level on the 7th postoperative day was found to be 962 mIU/ml. At the same time, the tumor rapidly recurred and disseminated to the liver. The patient died three months after the initial diagnosis.