Acute myeloid leukemia accounts for over 9,000 deaths yearly in the United States. The WHO classification of AML incorporates and interrelated morphology, cytogenetics, molecular genetics and immunologic markers in an attempt to construct a classification that is clinically and prognostically valid. Under this classification the requisite blast percentage in the marrow is > 20%. Hematopoietic stem cell transplantation is an established therapeutic modality in patients with AML. An alloreactive immunotherapeutic effect of donor cells has been demonstrated.