Inclusion Criteria:

1. Diagnosis or 1) Acute myeloid leukemia past first remission, in first or subsequent relapse, or induction failures, 2) Myelodysplastic syndromes with intermediate or high risk International Prognostic Scoring System score (IPSS scores) (16), and having failed previous chemotherapy, or 3) Chronic Myeloid Leukemia, Philadelphia-chromosome positive and having failed / being resistant to therapy based on Gleevec or other tyrosine kinase inhibitors.
2. Patient has not been administered intensive systemic chemotherapeutic drugs within 21 days prior to trial enrollment (BMT Day -9). Gleevec, alternative tyrosine kinase inhibitors, other nonmyelosuppressive agents, low dose cytarabine, hydroxyurea is permitted if indicated to control the leukemia. All tyrosine inhibitor- or other non-myelosuppressive agents have to be terminated at least one week prior to admission for this treatment.
3. No uncontrolled infection. Protocol PI will be final arbiter if there is uncertainty regarding whether a previous infection is resolved on appropriate antibiotics therapy.
4. age </= 60
5. A related or unrelated donor who is HLA-matched or mismatched in 1 HLA, A, B, C, DR or DQ locus is acceptable (i.e. at least a 9/10 matched related or unrelated donor, matched with molecular high-resolution technique per current standard for the BMT program).
6. ZUBROD performance status <2
7. Life expectancy is not severely limited by concomitant illness.
8. Left ventricular ejection fraction >/=45% No uncontrolled arrhythmias or symptomatic cardiac disease.
9. FEV1, FVC and DLCO >/= 50% of expected corrected for hemoglobin. In patients </= 7 years pulmonary function will be assessed per pediatric BMT routine
10. Serum creatinine </= 1.5 mg%.
11. SGPT </= 200 IU/ml, serum bilirubin and alkaline phosphatase within accepted laboratory standard normal limits or considered not clinically significant. No evidence of chronic active hepatitis or cirrhosis. If positive hepatitis serology, discuss with Study Chairman and perform liver biopsy pror to determining study eligibility.
12. Female patient is not pregnant (negative B-HCG pregnancy test in all women of child-bearing-potential in accordance with departmental routine).
13. Patient or patient's legal representative, parent(s) or guardian able to sign informed consent.

Exclusion Criteria:

1. Effusion or ascites estimated to be >1L prior to drainage.
2. HIV-positive.
3. Hepatitis C or HBsAg positive
4. Prior stem cell transplant after a myeloablative conditioning program (such as busulfan-based using a total dose of >/= 12 mg/kg given by mouth or >/= 10 mg/kg IV, or a total-body irradiation-based program.
5. Active or prior CNS leukemia
6. Biphenotypic acute leukemia.