Hematopoietic stem cell transplantation (HSCT) is an important therapy for a variety of malignancies including leukemias, lymphomas and advanced solid tumors, and non-malignant diseases. The therapeutic benefits of BMT are not only derived from the opportunity to give high doses of chemotherapy and/or radiation, but also from a so-called graft-versus-tumor (GVT) effect. Graft-versus-Host-Disease (GVHD) and immune deficiencies after BMT are important complications of allogeneic BMT. My laboratory uses mouse HSCT models to study clinically important problems in HSCT and test novel therapeutic strategies. At present, the major projects in the laboratory include the role of T cell homing and T cell cytolytic pathways in the development of GVHD and GVT and strategies to enhance post-transplant immune reconstitution.