Ovarian carcinosarcoma, also called a mesodermal mixed tumor or mixed Mullerian tumor, is a rare ovarian tumor that accounts for less than 2% of ovarian cancers. It is an aggressive tumor that combines a carcinomatous component with a sarcomatous component. Less than 400 cases have been reported in the literature. We report 01 case observed over five years at the department of obstetric and gynecology of the university hospital Hassan II. Ovarian carcinosarcoma has a worse prognosis than ovarian epithelial tumors. Its rarity explains that there is no consensus on its management. There is very little data available. The only prognostic factor found is the initial stage. The surgical management is a determining factor for the survival of the patients, this one must be as complete as possible. The sensitivity to the chemotherapy is lower, is about 20%. The survival at five years is lowered when the compared to epithelial tumors of the ovary