Eosinophilic granulomatosis with polyangiitis (previously called Churg-Strauss syndrome) is an ANCA-associated vasculitis (along with granulomatosis with polyangiitis and microscopic polyangiitis), although the presence of ANCA occurs in less than 50% of patients (usually anti-MPO). It is characterized by peripheral eosinophilia, sinusitis with polyposis, asthma, lung infiltrates, vasculitic skin involvement, glomerulonephritis, and vasculitic neuropathy. Myocarditis can lead to arrhythmias and heart failure if untreated. Eosinophilic granulomatosis with polyangiitis should be considered in patients with an unexplained peripheral eosinophilia and vasculitic features. Corticosteroids remain first-line treatment with azathioprine and methotrexate demonstrating efficacy for mild to moderate disease. Mepolizumab, an IL-5 inhibitor, is FDA approved for the treatment of eosinophilic granulomatosis with polyangiitis, although it has not been studied for severe life- or organ-threatening vasculitic disease manifestations (which generally require cyclophosphamide).