Idiopathic hypereosinophilic syndrome (HES) is a condition of unknown origin characterized by clinical manifestations attributable to eosinophilia and eosinophilic infiltration of tissues. Cardiac involvement is rare and threatening accounting for 33% to 43% of death in HES. Management of pregnant patients with HES is challenging and have rarely been reported, particularly in the setting of heart failure.We here report on the case of a 29-year-old woman with HES who developed severe endomyocardial fibrosis with heart failure during pregnancy. Outcome was favorable under treatment with prednisone and azathioprine.This case illustrates a favorable outcome of endomyocardial fibrosis during pregnancy.