Phase II Gleevec Idiopathic Hypereosinophilic Syndrome

Inclusion Criteria:- At study entry, absolute peripheral blood eosinophil count greater than upper limit of normal at the laboratory where the analysis is performed. * Patients must have symptomatic disease, e.g. signs or symptoms of organ involvement related to eosinophilia. Examples include pulmonary, cardiac, GI, or central nervous system disease, hepatomegaly, splenomegaly, or skin disease. * BCR-ABL-negative by PCR. * Patients are imatinib-naive. * Ability to understand and the willingness to sign a written informed consent document. * Ability to swallow capsules.\
 Exclusion Criteria:- Pregnant or nursing women. Patients of childbearing potential must have a negative pregnancy test prior to initiation of study drug. Male and female patients of reproductive potential must agree to employ an effective barrier method of birth control during the study and for 3 months following discontinuation of study drug. * Serum creatinine \>2.0. * Total serum bilirubin \>2.0 mg/dl. AST(SGOT) and ALT (SGPT) more than 2.5 x the upper limit of normal range (ULN) at the laboratory where the analyses is performed. * Presence of clonal T-lymphocyte population by PCR or southern blotting. * ECOG Performance Status Score \> or = to 3. * Busulfan within 6 weeks of starting treatment. * IFN-a within 14 days of starting treatment. * Low dose cytosine-arabinoside or vincristine within 14 days of starting treatment. * Hydroxyurea within 1 day of starting treatment. * Prednisone or other immunosuppressives (e.g. azathioprine, cyclosporine-A) within 14 days of starting treatment. * AML/ALL-type induction chemotherapy within 4 weeks of starting treatment * Persistent peripheral blood count toxicity of grade 2 or higher after receiving AML/ALL-type induction chemotherapy. * Treatment with other investigational agents within 28 days of starting treatment. * History of non-compliance to medical regimens. * Uncontrolled intercurrent illness including, but not limited to, ongoing or active infection, symptomatic congestive heart failure (Grade 3 / 4 New York Heart Association Criteria), unstable angina pectoris or cardiac arrhythmia, or psychiatric illness/social situations that would limit compliance with study requirements. * History of HIV-positivity.