Hepatoid adenocarcinoma is a rare variant of adenocarcinoma of the stomach. The tumor has been found to be an alpha-fetoprotein (AFP) producing carcinoma arising in extrahepatic organs, and it mimics hepatocellular carcinoma in terms of morphology and function. Vascular invasion, usually prominent, is often complicated by extensive liver metastases, and vascular permeation, especially in the veins, has been described as a characteristic finding of this tumor. A patient with hepatoid adenocarcinoma of the stomach with a huge mass is described. Gastrofiberscopy revealed an elevated lesion with a central depression on the greater curvature of the antrum and with extrinsic compression on the lesser curvature and the duodenum. Computed tomography revealed a large lobulated mass in the lesser curvature of the stomach, attached from the liver, gall bladder and porta hepatitis to the pancreas. The AFP serum level was markedly elevated. After a diagnosis was made of AFP-producing stomach carcinoma with huge lymph node metastasis, subtotal gastectomy with wedge resection of the liver, and cholecystectomy including the huge mass ware performed. Microscopically, the tumor and intraabdominal huge mass showed mainly hepatoid differentiation. The tumor showed immunohistochemical positivity for AFP and huge lesser omental metastasis with adhesion to the liver and extensive venous invasion. Lymph node metastasis was not found. According to these histopathological findings, the tumor was diagnosed as hepatoid adenocarcinoma of the stomach with venous invasion. We report this rare variant of adenocarcinoma of the stomach, which mimics hepatocellular carcinoma in its propensity for venous permeation.