Animal models and human studies of allogeneic hematopoietic cell transplantation (HCT) demonstrate that immunologic nonidentity between donor and recipient is responsible for a graft versus leukemia (GVL) effect that contributes to complete tumor eradication. A variety of immune cells have been implicated in the GVL effect including NK cells, B cells, and CD4(+) and CD8(+) T cells that recognize minor histocompatibility (H) or leukemia-associated antigens. Here we discuss strategies for employing T cells specific for minor H antigens to augment the GVL effect.