To determine the safety and efficacy of decitabine in patients with Philadelphia chromosome-positive chronic myelogenous leukemia accelerated phase that were previously treated with imatinib mesylate (STI 571) and became resistant/refractory or were found to be intolerant to the drug.

Inclusion:

• Histologically confirmed diagnosis of CML accelerated phase

• Ph chromosome-positive

• Previous treatment with imatinib mesylate resulting in:

  i) Hematologic Resistance / Hematologic Refractory: Based on a physician's (documented) decision to discontinue imatinib mesylate treatment due to failure of continued benefit or no benefit to the patient, ii) Imatinib Mesylate Intolerance: any toxicity resulting in a physician's (documented) decision to discontinue imatinib mesylate treatment.

• Patients must have recovered from the side effects of previous CML therapy for accelerated phase with the exception of hydroxyurea

• Age >/= 2 years

• Bilirubin \