Endometrial carcino-sarcoma is a rare rapidly growing mixed muellerian tumor. The pathogenesis of this tumor is not definitely known. However, the current explanation favors the theory of the growth of this tumor from pluripotential sub-epithelial cells. The incidence of the tumor is increased in post-menopausal women. Many of these women have a history of radiotherapy of the genital organs for benign gynaecological disease. A causal relationship between occurence of carcino-sarcoma and estrogen treatment as in carcinoma of the endometrium is not mentioned in the literature. The clinical signs and symptoms are non-specific as in many other malignant tumors of the uterine body. The prognosis is very bad. The average survival from the onset of the first symptoms is only a few months. The treatment of choice appears to be total abdominal hysterectomy and bilateral salpingo-oophorectomy. Radical operations and ancillary radiotherapy and chemotherapy do not appear to improve the survival rate. The extremely rare coincidence of a carcino-sarcoma in a young woman with Turner Syndrome gonadal dysgenesis after five years of treatment with estrogen led to the present case report.