We investigated the clinical and histologic characteristics of patients with ovarian serous adenocarcinofibroma. Because the tumors in both cases contained fibroma components; they were hard and clinically indistinguishable from uterine myoma, even by computed tomography. Both patients experienced relapses associated with tumors that originated outside the abdominal cavity (the subcutaneous abdominal wall in case 1, and the inguinal lymph nodes in case 2). The serum level of CA125 was normal or only moderately elevated at the first onset and relapse. The present cases suggest that the diagnostic features and clinical course differ between ovarian serous adenocarcinoma and serous adenocarcinofibroma.