Carcinosarcoma of the uterus is a rare gynaecological neoplasm, which is also known as malignant mixed mesodermal tumor. Traditionally this tumour has been regarded as a subtype of uterine sarcoma, and its origin remains controversial. The exact nature and prognosis was not clear in the past. It is believed that uterine carcinosarcoma have a Mullerian duct origin and have a capacity to differentiate into various mesenchymal and epithelial components. Regarding the histogensis, various theories have been given; of which 'conversion theory' was broadly accepted. Carcinosarcoma are mostly of monoclonal origin with the carcinomatous component being the driving force. This type of tumor is broadly divided into two groups, homologous and heterologous, depending on the characteristics of the stroma or mesenchymal components of endometrial tissue. It is more frequent in black women and postmenopausal women. Radiation is a possible etiological factor but the exact etiology is not known yet. However, tamoxifen may induce carcinogenesis in some patients. Its clinical feature is very similar to endometrial carcinoma i.e. postmenopausal vaginal bleeding, have a very aggressive behavior and a poor prognosis. This pelvic malignancy is treated by multimodality therapy including surgery, chemotherapy and radiotherapy. Here we are reviewing old concepts about the disease and modern understandings of the origin, classification, pathogenesis and recent advances in the treatment of the uterine carcinosarcoma.