Inclusion Criteria:

- Age 18 to 65 years.

- 8/8 or 7/8 HLA-identical matched sibling OR Allele level 8/8 (HLA-A, B, C, DRbeta1)
matched unrelated donor.

- Patients with high risk ALL in first complete remission, with high risk being defined
by the presence of t(4;11), t(9;22) or t(1;19) or patients presenting with extreme
hyperleukocytosis (WBC>500,000/ml) or partial remission after initial induction
therapy.

- Adult patients with acute non-lymphocytic Leukemia (ANLL) in first complete remission
with high-risk cytogenetics (monosomy chromosome 5 or 7, del(5q), abn(3q26), complex
karyotypic abnormalities) or failure to achieve complete remission after standard
induction therapy.

- All patients with ALL or ANLL in second or subsequent remission or partial remission
(<5% blasts in bone marrow as measured by flow cytometry).

- All patients with CML in chronic (failed interferon and/or Gleevec) or accelerated
phase.

- Patients with myelodysplastic syndrome with International Prognostic Scoring System
(IPSS) risk category of INT-1 or greater.

- Myelofibrosis with myeloid metaplasia

- Patients with severe aplastic anemia must have failed immunosuppressive therapy such
as cyclosporine plus anti-thymocyte globulin.

- Patients with a history of CNS disease must have been treated and have no active CNS
disease at the time of protocol treatment.

- ECOG performance status <2

- Patients must have adequate function of other organ systems as measured by:

- Creatinine clearance (by Cockcroft Gault equation [Appendix IV]) > 30ml/min. Hepatic
transaminases (ALT/AST) < 4 x normal, bilirubin < 2.0 mg/dl.

- Pulmonary function tests demonstrating FVC and FEV1 of >50% of predicted for age and
DLCO > 50% of predicted.

- Ejection fraction of >45% by echocardiogram, radionuclide scan or cardiac MRI.

- Patients must be HIV negative.

- Patients must not be pregnant.

Exclusion Criteria:

- Patients with > 5% blasts in bone marrow or peripheral circulation.

- Patients with rapidly progressive ANLL or ALL.