Hypereosinophilic syndrome is a leukoproliferative disease characterised by sustained overproduction of eosinophils. The three diagnostic criteria for this disorder are (1) Eosinophilia of greater than 1500 cells/ml, persisting for longer than 6 months, (2) lack of another diagnosis to explain the eosinophilia and (3) signs and symptoms of organ involvement. We report a 15-year-old boy who was diagnosed as Hypereosinophilic syndrome based on these criteria.