Background: Peutz-Jeghers syndrome is a rare syndrome which is inherited in a dominant manner. It is characterized by hamartomatous polyps of the gastrointestinal tract, hyperpigmented macules of the oral mucosa and an increased risk of developing neoplasms in the gastrointestinal tract, pancreas, breast and genital system. Women with Peutz-Jeughers syndrome often develop an ovarian sex cord tumor and cervical adenocarcinoma of minimal deviation adenoma malignum type. A case of a 58-year-old patient with Peutz-Jeghers syndrome and history of multiple malignancies (thyroid, breast and colon cancer) who presented with metrorrhagia is reported. The dilatation and curettage revealed endometrial adenocarcinoma. The patient underwent total abdominal hysterectomy with bilateral oophorectomy. The histologic examination showed an endometrioid endometrial adenocarcinoma that developed in atypical endometrial hyperplasia. The histologic examination of the right ovary revealed a sex cord tumor with annular tubules, measuring 3 cm. Sex cord tumors with annular tubules in patients with Peutz-Jeghers syndrome are usually small, bilateral tumors of the ovaries which have common characteristics with granulosa cell tumor and Sertoli cell tumor. Hyperestrogenism is a rather common finding with development of estrogen-dependent lesions.