Inclusion Criteria:

1. Patients must have histologically confirmed Acute Myeloid Leukemia (AML) or high risk
and previously treated Myelodysplastic Syndrome (MDS).

2. Patients with (1) refractory disease or (2) first relapse within 6 months of therapy
or (3) 2nd or more of relapse of Acute Myelogenous Leukemia (AML) or high risk
Myelodysplastic Syndrome MDS will be considered for the study.

3. Patients must have been off chemotherapy for 4 weeks prior to entering this study and
recovered from the toxic effects of that therapy, unless there is evidence of rapidly
progressive disease.

4. Age >=18 years. Deoxyribonucleic acid (DNA) methylation plays a significant role in
development, and the effects of azacitidine in children are not well described.

5. Patients must have normal organ as defined: Total bilirubin <2 mg, aspartate
aminotransferase (AST)/alanine aminotransferase (ALT) <2.5 x institutional upper
limit of normal, Creatinine <2 mg

6. Ability to understand and the willingness to sign a written informed consent
document.

7. Women of child bearing potential must have a negative serum pregnancy test prior to
azacitidine treatment.

8. Women of child bearing potential should be advised to avoid becoming pregnant and men
should be advised to not father a child while receiving treatment with azacytidine.

9. Eastern Cooperative Oncology Group (ECOG) performance status 0-2.

Exclusion Criteria:

1. Patients who have had chemotherapy or radiotherapy within 4 weeks (6 weeks for
nitrosoureas or mitomycin C) prior to entering the study or those who have not
recovered from adverse events due to agents administered more than 4 weeks earlier,
unless there is evidence of rapidly progressive disease. Patients may have received
hydroxyurea prior to entering the study.

2. Patients may not be receiving any other investigational agents for their leukemias.

3. Patients with active brain or meningeal disease should be excluded.

4. Known or suspected hypersensitivity to azacitidine or mannitol

5. Uncontrolled intercurrent illness including, but not limited to, ongoing or active
infection, or psychiatric illness/social situations that would limit compliance with
study requirements.

6. Pregnant women are excluded from this study because azacitidine is a Deoxyribonucleic
acid (DNA) methyltransferase inhibitor which has teratogenic or abortifacient
effects. Because there is an unknown but potential risk for adverse events in nursing
infants secondary to treatment of the mother with azacitidine, breastfeeding should
be discontinued if the mother is treated with azacitidine.