A case of hepatoid carcinoma of the ovary in a 61-year-old Japanese woman, who showed high serum levels of alpha-fetoprotein and CA125, is reported. Grossly, the left ovarian tumor, which measured 12 x 9 cm, was solid and multinodular. Histologically, the tumor resembled hepatocellular carcinoma by its architectural and cytological features. Liver cell differentiation was indicated functionally by the immunohistochemical detection of alpha-fetoprotein and protein induced by vitamin K absence or antagonist II (PIVKA-II) and by positive bile production, and the hepatocellular differentiation was structurally in accord with keratin 7, 8 and 18 expression. CA125 expression, commonly present in ovarian surface epithelial carcinomas, suggested that this neoplasm originated from ovarian common epithelial cells. There are only nine such cases in the literature. A review of these cases reveals that hepatoid carcinoma of the ovary occurs exclusively in postmenopausal women (mean age, 62.7 years) and that the prognosis is poor.