The hypereosinophilic syndrome is a multi-organ disease characterized by large counts of eosinophils in peripheral blood observed during at least six months without any evidence for other known causes of eosinophilia. Idiopathic hypereosinophilia is rare and is always diagnosed by exclusion of other disease. This work describes a man aged 21 years who was hospitalized at the Department of Dermatology because of skin manifestations resembling eczema and urticaria. High eosinophil counts in this patient necessitated a wide array of diagnostic tests. The hypereosinophilic syndrome was diagnosed after more than 12 months of follow-up and exclusion of other causes. Corticosteroids and hydroxycarbamide were administered as first-line therapy. Unfortunately, the patient was unresponsive to steroids. Improvement in peripheral eosinophilia after Glivec therapy correlated with improved clinical status.