Hypereosinophilic syndrome represents a range of rare and heterogeneous disorders sharing three features: peripheral eosinophil count higher than 1.5 x 109/L for over 6 months, evidence of organ involvement and absence of other causes of eosinophilia, such as allergy, parasite infestation and malignancy. Hypereosinophilic syndrome may present with various cutaneous abnormalities. Over 50% of such patients have pruritic erythematous macules, papules, plaques, wheals, nodules, or other skin lesions during the course of the disease. The diagnosis of hypereosinophilic syndrome may be delayed or missed because the association between cutaneous lesions and hypereosinophilic syndrome is not appreciated. The presence of eosinophils in normal tissues is surprisingly selective. Eosinophil infiltration or degranulation is not seen in skin samples from normal persons. The treatment goal for patients with hypereosinophilic syndrome is to provide relief of symptoms and improvement in organ function while keeping eosinophils in peripheral blood at 1000-2000/mL and minimizing side effects.