Hypereosinophilic syndrome (HES) is a rare entity of unknown etiology that may cause a multitude of problems, from skin rash to organ failure, due to eosinophil infiltrate of tissues. Information on the interaction of hypereosinophilia and pregnancy in patients with established HES is very limited. Here we report a case of a woman with a seven year history of HES whose pregnancy resulted in the delivery of a healthy infant without complications, and no evidence of elevated eosinophils in the infants blood. During pregnancy the patient experienced significant reduction of eosinophils in her blood and resolution of signs and symptoms related to hypereosinophilia.