Pertuzumab is a monoclonal antibody that represents the first among a new class of agents known as human epidermal growth factor receptor (HER) dimerization inhibitors. This is the first systematic review according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines to synthesize all available data of pertuzumab in breast cancer. The search strategy retrieved 11 studies that evaluated pertuzumab. One study was conducted in the neoadjuvant setting (417 patients), whereas all the others dealt with patients with recurrent, metastatic, or refractory disease (1023 patients). Six studies were conducted in HER2(+) breast cancer population (1354 patients), whereas 5 studies (86 patients) were conducted in HER2(-) (or unknown HER2 status) disease. Pertuzumab is the most recent agent approved by the US Food and Drug Administration in combination with trastuzumab and docetaxel for the treatment of patients with HER2(+) metastatic breast cancer who have not received prior anti-HER2 therapy or chemotherapy for metastatic disease. This approval has been based on data from a phase III Clinical Evaluation of Pertuzumab and Trastuzumab (CLEOPATRA) study. The antitumor activity with the significant reduction in the risk of progression or death, as reflected upon the increase of 6.1 months in median progression-free survival, indicates that pertuzumab may provide an avenue for achieving additional benefit for patients with HER2(+). Moreover, pertuzumab seems to have a putative role in the management of patients with HER2 who are resistant to trastuzumab. The promising role of pertuzumab in the neoadjuvant and adjuvant settings remains to be further investigated and established in the future.