A case of a right ovarian tumor in a 64-year-old patient showing high blood levels of alpha-fetoprotein (AFP) is reported. Histologically, the tumor resembled hepatocellular carcinoma with hyaline globules. Localization of AFP was detected by the immunoperoxidase method. Electron microscopically, the rough-surfaced endoplasmic reticulum had developed into a meshwork, and the mitochondria were present within this meshwork. Because a transition from adenocarcinoma to a region resembling hepatocellular carcinoma was observed, this tumor was considered to originate as a common epithelial carcinoma. In the blood, 67% of the AFP was bound with concanavalin A (Con A), and the fraction pattern obtained by lentil agglutinin affinity chromatography (LCA) was of the germ cell type. From these results, the current case may be labeled clinicopathologically a hepatoid carcinoma of the ovary as described by Ishikura and Scully.