Angioedema with hypereosinophilia syndrome has a dramatic clinical presentation that may result from T-cell dysregulation and/or eosinophil dysfunction. Symptoms may be either episodic or persistent and are usually responsive to systemic glucocorticosteroid therapy. This diabetic patient had a dramatically severe presentation, responsive to high-dose steroids but relapsing when prednisone was tapered. To decrease his risks from long-term steroids, a therapeutic trial of intravenous immunoglobulin (IVIG) was tried, and a slow taper off of glucocorticosteroids achieved a prolonged remission. A brief recurrence and subsequent remission of eosinophilia and symptoms were associated with changes in the IVIG preparation lot and source. We conclude that some cases of angioedema with hypereosinophilia syndrome may be highly responsive to IVIG therapy and, furthermore, that specific sources and/or lots of IVIG may have significantly different immunoregulatory properties.