Adoptive immunotherapy may be performed with either autologous or allogeneic lymphocytes. Autologous cellular immunotherapy is hindered by the inability to break anergy or self-tolerance. Advances in this area have focused on the use of tumor-specific lymphocytes activated by antigen-pulsed or transgene modified dendritic cells. Allogeneic cellular immunotherapy is effective even with the use of non-specific and unactivated donor lymphocytes. Allogeneic cellular therapy is, however, complicated by graft-versus-host disease (GVHD). Advances in allogeneic immunotherapy will require better control of GVHD.