Long-term tolerance is potentially an ideal in organ transplant. Achieving this leads us to eliminate immunosuppressive therapies and their associated side effects. Although most succession in this field belongs to mixed chimerism methods of tolerance induction, regulatory T cells and (T-reg)-based methods also have been demonstrated to prevent organ rejection and lead to transplant tolerance through different mechanisms. In contrast to chimeric protocols (which require bone marrow transplant), T-reg-mediated protocols do not aggressively manipulate blood and the immune system. Most treatment has been done for graft-versus-host disease after hematopoietic stem cell transplant. This review describes different types and mechanisms of action and clinical strategies using T-regs to induce transplant tolerance.