Three cases of epididymal adenomatoid tumor are presented. The adenoid compositions of the tumors lined by epithelial cells showed a canalicular pattern with large vascular spaces, tubular pattern with glandlike regions or plexiform pattern with connective tissue strands. Immunohistochemistry demonstrated positive cytoplasmic staining for keratin, but negative for carcinoembryonic antigen and factor VIII-related antigen in each neoplastic tissue. These findings support the mesothelial origin of the epididymal adenomatoid tumors.