Anti-HER2 treatment for HER2-positive breast cancer has changed the natural biology of this disease. This Series article reviews the main achievements so far in the treatment of both metastatic and early HER2-positive breast cancer. The success of neoadjuvant therapy in HER2-positive early breast cancer is especially acknowledged, as pertuzumab has been approved on the basis of a higher proportion of patients achieving a pathological complete response with pertuzumab and trastuzumab than with trastuzumab alone in a neoadjuvant study. Event-free survival after the confirmatory adjuvant trial completed recruitment was numerically better with pertuzumab plus trastuzumab than with trastuzumab alone. With survival rates of almost 5 years in women with metastatic HER2-positive breast cancer and 75% of patients achieving a pathological complete response, new treatments in the past decade have clearly improved the prognosis of HER2-positive breast cancer. Despite these achievements, however, the persisting high toll of deaths resulting from HER2-positive breast cancer calls for continued, intensive clinical research of newer therapies and combinations. © 2016 Elsevier Ltd.