Although the treatment of patients with early-stage breast cancer is provided by a multidisciplinary team, surgeons must ensure they are well informed about all aspects of patient care. For example, understanding the importance of human epidermal growth factor receptor 2 (HER2) gene amplification and/or protein overexpression and the effect on patient prognosis can guide therapeutic decision making. In addition, surgeons should also be knowledgeable about the wide variety of available postsurgical treatments, from traditional chemotherapy and radiotherapy to novel agents such as the HER2-targeted monoclonal antibody trastuzumab. Trastuzumab was recently approved for adjuvant treatment of invasive, HER2-positive, node-positive breast cancer. Its approval was based on the combined results of two large-scale trials, which demonstrated that adding trastuzumab to chemotherapy significantly improves disease-free and overall survival. Knowledge about the indications, schedules, and safety profiles of therapies such as trastuzumab will enable surgeons to optimize the timing of surgery in relation to these therapies, and to make informed decisions about the team member to whom a particular patient should ideally be referred for postsurgical care. In the future, results from large-scale trials evaluating the clinical utility of neoadjuvant trastuzumab will become available. Early results from ongoing phase III trials of the addition of trastuzumab to presurgical chemotherapy suggest that high response rates, including pathologic complete responses, are achievable. If trastuzumab is approved for use in neoadjuvant regimens, the need for surgeons to be well informed about the appropriate use of this particular agent will become even more important.