Treatment of metastatic breast cancer (MBC) remains one of the major challenges in cancer care. Chemotherapeutic agents currently approved for the treatment of invasive disease may exhibit initial efficacy; however, the development of resistance to therapy and concerns over tolerability are common and generally limit treatment options available to physicians and patients. Novel chemotherapeutic agents are, therefore, necessary to increase survival, delay disease progression, and improve tolerability. Eribulin mesylate (E7389) is a novel microtubule dynamics inhibitor with a unique mechanism of action that has shown antitumor efficacy and a manageable tolerability profile in clinical trials. Importantly, eribulin is the only single agent to date that has been shown to prolong overall survival in patients with heavily pretreated MBC. This review will discuss eribulin, with focus on the potential it has to address the specific treatment needs of patients with MBC who are refractory to conventional chemotherapies.