This consensus statement is a joint initiative of the Spanish Society of Pathology (SEAP) and the Spanish Society of Medical Oncology (SEOM). It revises and updates the recommendations for the use of biomarkers in the diagnosis and treatment of breast cancer. The group of experts recommends that, in all cases of breast cancer, the histologic grade and the alpha-estrogen receptor (ER), progesterone receptor, Ki-67 and HER2 status should be determined, in order to assist prognosis and establish therapeutic options, including hormone therapy, chemotherapy and anti-HER2 therapy. One of the four available genetic prognostic platforms (MammaPrint®, Oncotype DX®, Prosigna® or EndoPredict®) may be used in node-negative ER-positive patients to establish a prognostic category and decide, together with the patient, whether adjuvant treatment be limited to hormonal therapy. Newer technologies, including next generation sequencing, liquid biopsy, tumour infiltrating lymphocytes or PD-1 determination, are still investigational.