<b>PURPOSE</b>: Leiomyosarcoma of the breast is extremely rare. To date, the factors that are predictive of patient prognosis have not been identified. To clarify the nature of leiomyosarcoma of the breast, and also to establish the proper treatment strategy, we report this case We report this case while discussing The Clinical presentation, diagnosis, therapy and pathologic feature. <b>INTRODUCION</b>: Sarcomas comprise less than 1% of all primary breast neoplasms and only a minority of these are leiomyosarcomas. There were only 35 cases being reported in English literature. The mainstay of treatment is surgical excision with clear margins and longterm followup is essential. Its prognosis is better compared to other breast sarcoma. <b>CASE PRESENTATION</b>: We report a case of primary leiomyosarcoma of the breast occurring in young female patient which was successfully treated by surgery and radiotherapy. <b>CONCLUSION</b>: According to literature data, primary leiomyosarcoma is characterized by a better prognosis compared with other breast sarcomas, To date, the factors that are predictive of patient prognosis have not been identified. .The rarity and diagnostic difficulty imposed a multidisciplinary approach