Sweet's syndrome is a neutrophilic dermatosis characterized clinically by raised, erythematous, tender lesions on the face, neck, upper thorax and extremities. Several diseases have been associated with this entity. We report a case of Sweet's syndrome associated with chronic myelogenous leukemia: a 48-year-old woman who developed recurrent skin lesions 3 years after the diagnosis of chronic myelogenous leukemia. Progression to an accelerated phase of the disease was detected 3 months after the beginning of the skin lesions. This case shows the convenience of evaluation and closer follow-up of patients with chronic myelogenous leukemia who develop skin lesions, especially if these lesions are recurrent.