We report the treatment course of a 29-year-old man who has had unique oscillating FIP1L1-PDGFRA fusion gene-negative hypereosinophilic syndrome (HES) for nearly 6 years. His periodic oscillating pattern of eosinophilia associated with angioedematous soft tissue swelling has shown two to three seasonal peaks (>15,000/μL absolute eosinophil counts [AEC]) a year. Initially, the patient, who was thought to have distinct HES not compatible with previously described cases, did not respond to treatment except for a temporary response to imatinib mesylate. For 6 years, from 2005 to 2010, he was treated with a combination of oral cyclosporine A, suplatast tosilate, and a small dose of prednisolone, which significantly reduced the peak heights of AEC as well as blunting the oscillating patterns.