Background: The causes of hypereosinophilia in children, the definition of hypereosinophilic syndrome and eosinophilic leukemia are introduced. Material/Methods: A rare case of hypereosinophilic syndrome (HES) with organ involvement in a 2-year-old child is presented. Discussion of the difficulties in diagnosis and therapeutic procedures in HES has been undertaken. Conclusions: Good response to corticosteroids in the reported case and the necessity of further observation is emphasized.

Keywords: Hypereosinophilic Syndrome, eosinophilic leukemia