RATIONALE: Drugs used in chemotherapy, such as azacitidine, work in different ways to stop the growth of abnormal cells, either by killing the cells or by stopping them from dividing. PURPOSE: This phase II trial is studying how well azacitidine works in treating patients with myelofibrosis.

OBJECTIVES: Primary * Determine the efficacy of azacitidine in patients with myelofibrosis (MF) with myeloid metaplasia. * Evaluate the safety of azacitidine in these patients. Secondary * Evaluate pertinent biologic characteristics of MF before and during therapy with azacitidine. * Assess the effects of study treatment on constitutional symptoms in these patients. * Estimate time to event distributions for overall survival and progression. OUTLINE: Patients receive azacitidine subcutaneously once daily on days 1-5. Treatment repeats every 4 weeks for up to 12 courses in the absence of disease progression or unacceptable toxicity. After completion of study treatment, patients are followed periodically for up to 3 years. PROJECTED ACCRUAL: A total of 35 patients will be accrued for this study.