To determine the safety and efficacy of decitabine in patients with Philadelphia chromosome-positive chronic myelogenous leukemia chronic 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 chronic 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 chronic phase with the exception of hydroxyurea
• Age >/= 2 years
• Bilirubin \