Context: Thecomas are benign tumors that account for less than 1% of all ovarian neoplasms. The association of ovarian thecoma with sclerosing peritonitis is rare. Case Report: We report the case of a 33-year-old woman, with a two-month history of increasing abdominal volume. Ultrasound showed a complex pelvic lesion and laboratory analysis detected elevated serum CA 125 levels. The patient underwent total abdominal hysterectomy with bilateral salpingo-oophorectomy and peritoneal biopsy. Histopathological analysis revealed the presence of luteinized thecoma of both ovaries associated with sclerosing peritonitis. Copyright © 2008, Associação Paulista de Medicina.1262123125Bianco, R., de Rosa, G., Staibno, S., Somma, P., Bianco, A.R., Ovarian luteinized thecoma with sclerosing peritonitis in an adult woman treated with leuprolide and toremifene in complete remission at 5 years (2005) Gynecol Oncol, 96 (3), pp. 846-849Clement, P.B., Young, R.H., Hanna, W., Scully, R.E., Sclerosing peritonitis associated with luteinized thecomas of the ovary. A clinicopathological analysis of six cases (1994) Am J Surg Pathol, 18 (1), pp. 1-13Iwasa, Y., Minamiguchi, S., Konishi, I., Onodera, H., Zhou, J., Yamabe, H., Sclerosing peritonitis associated with luteinized thecoma of the ovary (1996) Pathol Int, 46 (7), pp. 510-514del Peso, G., Bajo, M.A., Gil, F., Clinical experience with tamoxifen in peritoneal fibrosing syndromes (2003) Adv Perit Dial, 19, pp. 32-35Nishida, T., Ushijima, K., Watanabe, J., Kage, M., Nagaoka, S., Sclerosing peritonitis associated with luteinized thecoma of the ovary (1999) Gynecol Oncol, 73 (1), pp. 167-169