Twenty-five peritoneal tumors in women are described. All were partly or entirely of papillary or tubulopapillary structure and multifocal. Eight were unusually well-differentiated mesotheliomas. This appearance was associated with indolent behavior. In 10 cases the growth closely resembled serous papillary carcinoma, including the frequent presence of psammoma bodies, but the ovaries were free of primary tumor. The latter group of tumors progress rapidly and are thought to be derived from extraovarian mesothelium with müllerian potential. Four further cases showed some resemblance to ovarian papillary carcinoma. Only three tumors in the entire series (12%) closely resembled papillary or tubulopapillary diffuse malignant mesothelioma of the type that occurs in the pleural cavities in both sexes. The histopathologic spectrum of papillary tumors of peritoneum in women is extensive, and mesothelial tumors of the type known to be associated with asbestos are rare.