A 63 years - old woman affected by severe eosinophilic asthma associated with EGPA presented refractory respiratory symptoms, resistant to high dose oral corticosteroid treatment. A significant hyper-eosinophilia was present at the blood test, and the ACT score was steadily low, despite the maximal dose of inhalation therapy. The CT chest scan showed a persistent diffuse bronchial wall thickening, pulmonary infiltration and paranasal sinusitis. We report here the rapid onset of effect of benralizumab 30 mg in a monthly subcutaneous injection in reducing patient's symptom, inducing regression of CT scan abnormalities, determining a steroid sparing effect and improving lung function tests after 3 months of therapy. A fast and stable reduction of peripheral eosinophilia associated with an increase in ACT score were also documented after the first dose of benralizumab.