The aim of this study is to investigate the value of immunohistochemical methods in the differential diagnosis of primary and metastatic ovarian carcinoma of gastrointestinal origin. Clinicopathologic features of 15 cases in the diagnosis of which we used cytokeratin 7 and 20, carcinoembryonic antigen and CA 12.5, are evaluated. In these cases light microscopic diagnosis is confirmed by the immunohistochemical method and in some, the initial diagnosis is changed. In conclusion, the use of an immunohistochemical panel of antibodies mentioned above is useful when used as a complementary method with the light microscopic features.