The aim was to evaluate baseline demographic, clinical, and laboratory characteristics, treatment modalities, and outcome of children with idiopathic hypereosinophilic syndrome (HES) followed up in our center. Children who fulfilled the criteria of idiopathic HES followed up at Hacettepe University Faculty of Medicine, Pediatric Hematology Department between June 2004 and October 2013 were included in this study. Medical records of all children with idiopathic HES were reviewed to obtain regarding data. The mean age of 6 children with idiopathic HES was 52.8 +/- 44.3 months (13 to 132 mo) at diagnosis. Among 6 children with idiopathic HES; 2 had pulmonary involvement; 1 had cardiac and pulmonary involvement and splenomegaly; 1 had cardiac involvement and hepatosplenomegaly; 1 had cardiac and central nervous system involvement; and 1 had skin involvement. The mean follow-up duration was 36.5 +/- 31.4 months. Methyl prednisolone (MP) was used for the first-line therapy. Complete response was achieved with MP in 3 children. All steroid responsive children are alive; whereas 3 children who did not respond to MP had expired. In conclusion, cardiac and pulmonary involvement is the major causes of mortality in HES. Resistance to steroid therapy indicates poor prognosis.