Over the years, the role of B cells in the host immune response to malignancy has been overshadowed by our focus on T cells. Nevertheless, B cells play important roles as antigen-presenting cells and in the production of antibodies. Furthermore, B cells can function as effector cells that mediate tumor destruction on their own. This review will highlight the various functions of B cells that are involved in the host response to tumor. J. Surg. Oncol. 2012;105:431–435. © 2011 Wiley Periodicals, Inc.