Malignant Mixed Mullerian Tumour of the Ovary (OMMMT), also referred to as carcinosarcoma is a very rare tumour accounting for less than 1% of all ovarian cancers. Due to the rarity of OMMMT, little is known about the disease course and outcome of women with these tumours. It is important to evaluate because of its aggressive behaviour with extremely unfavourable prognosis. These tumours are composed of both malignant epithelial and mesenchymal elements. Current data in the literature is still limited to small case series and case reports, therefore, its optimal treatment is somewhat controversial. In the current report, we introduce a case of OMMMT which was successfully treated with Platinum-based combination chemotherapy after optimal cytoreductive surgery. The clinical manifestations, pathologic characteristics, diagnosis and management of these tumours are reviewed here. Although the most effective treatment is currently unknown, optimal cytoreductive surgery and platinum-based chemotherapy appears to improve the outcomes. Despite the aggressive nature of this tumour and its poor response to the treatment, management works best when cancer is found early. The stage of the disease is the most important prognostic factor. Therefore, the crucial question is how to diagnose the cancer at earlier stages rather than seeking the optimal treatment.