Eosinophilic granulomatosis with polyangiitis (EGPA), is a rare necrotizing vasculitis predominantly involving small to medium size vessels with eosinophilia and necrotizing granulomatous inflammation involving the respiratory tract, mepolizumab is an anti-interleukin-5 monoclonal antibody that binds to interleukin-5 and stops it from interacting with its receptor on the surface of eosinophils. To demonstrate that, we present a case of young female known to have bronchial asthma and chronic sinusitis since childhood presented with shortness of breath, found to have EGPA, her condition deteriorated and finely she was treated with Mepolizumab, which showed that it has efficacy in treating patients with EGPA.