A case of a 41 years old woman with a benign mesothelioma of the superficial epithelium of the ovary, is presented. The tumor was expanded at the bottom of the cul de sac. It did not invade the rectum, uterus or vagina and it has not been recurrent, and there are not metastasis after y 6 years post operatively. Morphologically, the neoplasia is created by papillae invested with cells of mesothelial appearance, which contain a small amount of glycogen and acids mucopolysaccharide. With immunoperoxidase keratin is shown and at the electronic microscope some desmosomes and microvillus, are identified. The histogenesis of the tumor examined, and the differential diagnosis between mesothelioma and superficial papillary carcinoma of the ovary, is considered.