Abstract: Objective To improve the understanding of the clinical manifestations of idiopathic hypereosinophilic syndrome (IHES).Methods A case diagnosed wih IHES was reported and the related literature was reviewed.Results A 27-year old man came to our hospital for the complaint of fever,cough for one week and bloody phlegm for one day.His blood routine test revealed hypereosinophilic.The chest CT scan indicated pleural effusion in both lungs and pericardial effusion.He was diagnosed as IHES.By given methylprednisolone,the eosinophil counts didn't decline obviously,and the symptom was not relieved.Then the serum FIP1L1/PDGFRα fusion gene was detected and it showed positive result.The methylpredmsolone treatment was changed to Gleevec.Then the eosinophil counts of the patient returned to normal.Conclusions IHES is uncommon.Its clinical manifestation is not typical.We should improve the recognition of IHES.