A 49-year-old patient presented with an adnexal mass. Endometrial curettage showed a proliferative phase and suspicious fragment resembling Arias Stella reaction. Laparotomy revealed an extensive nodular intra-abdominal tumor involving the bilateral ovaries. Microscopic findings were similar to the suspicious endometrial fragment in the curettage specimen. Histochemical and immunohis­tochemical studies confirmed the diagnosis of diffuse malignant mesothelioma with metastasis to the endometrium. This is the first reported case to our knowledge in the English literature.