Despite more than four decades of effort, the improvement in survival in metastatic breast cancer has been modest. Recently, however, new drugs such as the taxanes have emerged as pivotal agents in the treatment of metastatic disease and they are now being investigated in the adjuvant setting. In addition, the introduction of molecularly targeted therapies such as trastuzumab provides a new paradigm for the development of biologic treatments. The incorporation of trastuzumab into new combination regimens based on potential molecular synergies is a focus of current research.