Rationale: Hepatoid adenocarcinoma (HAC) is a rare extrahepatic adenocarcinoma that histologically resembles hepatocellular carcinoma (HCC). HAC of peritoneal cavity can present as a solitary mass or disseminated nodules indicating different treatment. Patient concerns: In this study, we present the cases of a 29-year-old man and a 64-year-old woman who suffered from HAC. Diagnosis: The serum alpha-fetoprotein (AFP) of both patients and ascites of 1 patient were markedly elevated. One patient presented with multiple nodular disseminated in the peritoneal cavity and the other patient has a mass between the left diaphragm and the spleen on computed tomography and magnetic resonance imaging. Intervention: The first patient underwent laparoscopic examination and multiple nodules were found in the peritoneal cavity, and only received chemotherapy. The second patient underwent surgery and resected the mass between left diaphragm and the spleen. Outcome: Histological examinations showed the nodule of the peritoneal cavity and mass belong to moderately differentiated HCC. HAC has a poor prognosis, but the 2 patients responded well to treatment. Lesson: HAC is frequently associated with elevated serum AFP without neoplasm in the liver. Histological and Immunohistochemistry examinations can help differential diagnosis.