In the past month, a female patient was presented with progressively worsening abdominal distension accompanied by nausea, vomiting, and significant body weight loss. Abdominal ultrasonography and computed tomography revealed dilatation of biliary tract and a 4 cm cyst-like mass at the left hepatic lobe contiguous to the gastric wall. Esophagogastroduodenoscopy revealed a large ulcerative mass covered with mucin-like fluid over the central depressed area at the anterior wall of her gastric body. Pathologic report demonstrated adenocarcinoma with prominent glandular differentiation and mucin production. Mucin-producing cholangiocarcinoma with direct stomach invasion was the most likely diagnosis. To our knowledge, only few reports on mucin-producing cholangiocarcinoma with direct invasion into the stomach have been presented in extant literature.