Maximal chemoradiotherapy may not be sufficient for eradication of disease in AML/MDS.

Host-versus-graft tolerance may be accomplished without myeloablation by a window of immunosuppression allowing engraftment of donor stem cells.

Following engraftment, alloreactive donor lymphocytes may be effective against AML and MDS, despite resistance of tumor cells to chemoradiotherapy.

Graft-versus-leukemia (GVL) effects may be induced by alloreactive donor T cells in tolerant mixed chimeras; hence, myeloablative conditioning may not be mandatory.

Following NST, donor lymphocyte infusion (DLI) may eliminate residual or recurrent leukemia.

NST may be applied after failure of earlier myeloablative BMT or subsequent to autologous BMT for optimal tumor debulking.

NST may offer an easier, safer and more effective option for inducing GVL effects especially at the stage of minimal disease.