Sweet's syndrome (acute febrile neutrophilic dermatosis) is characterized by an acute onset of erythematous plaques, fever, and leukocytosis. This syndrome has been reported to be associated with leukemia including chronic myelogenous leukemia (CML). Sweet's syndrome seen in patients with leukemia is usually associated with active and/or refractory disease. Imatinib Mesylate (STI-571, Gleevec) is widely used for therapy of CML. In this case report, CML cell infiltration of the skin was documented by fluorescence in situ hybridization (FISH) analysis in a patient with chronic-phase CML on Imatinib Mesylate (STI-571, Gleevec), who was at the time in molecular remission.