Introduction: Breast cancer is the most common cancer in women worldwide. Despite the development of targeted therapies that have significantly improved survival, effective breast cancer evaluation is still challenging due to the complexity of this disease. Liquid biopsy might allow the noninvasive real-time monitoring of the tumor course and response to therapy. Areas covered: This review summarizes the latest advances on the various circulating analytes used as liquid biopsy (circulating tumor cells and tumor DNA, and more recently extracellular vesicles) for breast cancer work-up. Several studies have shown that in breast cancer, liquid biopsy can be used to predict disease progression or relapse and to monitor the treatment response. Moreover, circulating analytes are more easily accessible than tissue biopsies and might represent a powerful source of specific knowledge. Expert opinion: The new evidence coming from the increasing number of clinical trials, and the continuous improvements in the technologies to isolate these tumor-derived analytes should strengthen the role of liquid biopsy in the clinic for personalized medicine of breast cancer.