Inclusion Criteria:

1. Pathological MDS either de novo or secondary, fitting any of the FAB classifications,
confirmed by institutional pathologist within 2 weeks prior to start of treatment.
Patients with 5% bone marrow blasts must also meet one of the following criteria:

- Symptomatic anemia with either hemoglobin less than 10.0 g/dL or requiring RBC
transfusion

- Thrombocytopenia with a history of two or more platelet counts < 50,000 / µL or
a significant hemorrhage requiring platelet transfusions, or

- Neutropenia with two or more absolute neutrophil counts less than 1,000 /µL.

2. ECOG performance status of 0-2.

3. Must give written informed consent indicating their awareness of the investigational
nature of this study and its potential hazards.

4. Adequate renal and hepatic function (creatinine <= 150% of institutional upper limit
of normal, total bilirubin <= 150% institutional upper limit of normal, AST <= 200%
institutional upper limit of normal).

5. Life expectancy of at least 12 weeks.

6. Have not received any chemotherapy within 4 weeks of study enrollment and must have
recovered from any treatment-related toxicities.

7. Women of childbearing age must have a negative serum pregnancy test prior to
initiating therapy.

8. Sexually active women of childbearing potential must use effective birth control
during the trial and for an appropriate period after the trial.

9. Men must be willing to avoid fathering a new child while receiving therapy with
azacitidine.

10. >=18 years, no upper age limit

11. Individuals who are candidates for hematopoietic stem cell transplantation and who
meet all other study criteria may participate in the study and receive intravenous
azacitidine alone as a treatment prior to transplantation.

Exclusion Criteria:

1. Known CNS leukemia.

2. Previously received Azacitidine (Vidaza®, Pharmion Corp., Boulder CO) or decitabine
(Dacogen®, MGI Pharma Inc. Bloomington, MN).

3. Known or suspected hypersensitivity to azacitidine or mannitol.

4. Receiving any other investigational agents within 30 days of first dose of study
drug.

5. Uncontrolled intercurrent illness including, but not limited to, ongoing or active
infection, congestive heart failure of NYHA class 3 or 4, unstable angina pectoris,
cardiac arrhythmia, or psychiatric illness/social situation that would limit
compliance with study requirements.

6. Known positive serology for HIV.

7. Had radiotherapy within 14 days prior to study enrollment.

8. Known presence of hepatic tumors.

9. <18 years of age

10. Exclude women who are pregnant or breast feeding.