Episodic angioedema with eosinophilia is a rare syndrome, characterized by periodic attacks of fever, myalgia, angioedema, and oliguria, associated with an increased eosinophil count. The pathogenesis of this disorder is incompletely understood. We describe an additional patient with episodic angioedema and eosinophilia, and review the literature regarding the clinical features and treatment of this disease. Previous hypotheses regarding disease mechanisms are discussed. In our patient, we found high basal levels of interleukin-1 (IL-1) and soluble interleukin-2 receptor (sIL-2R), with further increases in levels of both mediators during attacks. We suggest that IL-1 and T cell activation may play a role in the pathophysiology of episodic angioedema with eosinophilia.