Primary systemic treatment is a fundamental part of breast cancer therapy, and it is applied to non-surgical and locally advanced tumours as well as surgical tumours to increase the likelihood of conservative treatment. Its aim is to achieve the best possible survival with better cosmetic results and with the lowest number of treatment-related secondary effects. Before treatment is started, it is necessary to attain the best knowledge of the biological features and locoregional extension of the tumour. To do so, it is necessary to obtain a biopsy of the lesion with a wide bore needle,as well as good radiological knowledge of the disease.Therefore, currently, the use of a dynamic magnetic resonance imaging(MRI) of the breast should be included in all cases. In addition, before it is started,especially in those tumours in which conservative treatment is considered, one or several radiopaque markers should be put into place to make it possible to locate the area to be treated if there is a considerable or complete response. Systemic treatment is mainly based on combined chemotherapy with anthracyclins and taxanes, in addition to some biological agents with demonstrated efficiency for increasing the likelihood of complete disease response(trastuzumab in patients with Her-2/neu overexpression). However, there is room for neoadjuvant hormone treatment, in patients with hormone receptor overexpression, especially in those cases in which chemotherapy is contraindicated as well as in elderly patients with a relatively short life expectancy. The assessment of preoperative treatment should be based on adequate radiological tests, and nowad these should include MRI before taking decisions about adequate surgical treatment. The objective of primary treatment is to be able to increase survival and improve the chances of local treatment in the case of locally advanced treatment, achieving results that are at least equal to those of adjuvant treatment in the case of surgical tumours, but with greater chances of conservative surgery. Although the objective is survival, achieving complete pathological response seems to be a reasonable related objective, although these are more closely linked in some tumour subtypes. Primary systemic treatment is a fundamental part of breast cancer therapy, and it is applied to non-surgical and locally advanced tumors as well as surgical tumors to increase the likelihood of conservative treatment. Its aim is to achieve the best possible survival with better cosmetic results and with the lowest number of treatment-related secondary effects. Before treatment is started, it is necessary to attain the best knowledge of the biological features and locoregional extension of the tumour. To do so, it is necessary to obtain a biopsy of the lesion with a wide bore needle, as well as good radiological knowledge of the disease. Currently, currently, the use of a dynamic magnetic resonance imaging (MRI) of the breast should be included in all cases. in those tumours in which conservative treatment is considered, one or several radiopaque markers should be put into place to make it possible to locate the area to be treated if there is a considerable or complete response. Systemic treatment is mainly based on combined chemotherapy with anthracyclins and taxanes, in addition to some biological agents with demonstrated efficiency for increasing likelihood of complete disease response (trastuzumab in patients with Her-2 / neu overexpression). However, , there is room for neoadjuvant hormone treatment, in patients with hormone receptor overexpression, especially in those cases in which chemotherapy is contraindicated as well as in elderly patients with a relatively short life expectancy. The assessment of preoperative treatment should be based on adequate radiological tests , and nowad these should include MRI before taking decisions about adequate surgical treatment. achieving objective that primary disease is able to increase survival and improve the chances of local treatment in the case of locally advanced treatment, achieving results that are at least equal to those of adjuvant treatment in the case of surgical tumoralthough the objective is survival, achieved complete pathological response seems to be a reasonable related objective, although these are more closely linked in some tumor subtypes.