Severe asthma affects between 5% and 10% of patients with asthma worldwide and requires best standard therapies at maximal doses, but there is a subgroup of patients refractory to all treatments. We share a case report of a 53-year-old woman with a history of severe allergic asthma that progressively worsened over the years despite the best therapy. She had been hospitalized 35 times, including nine admissions to the respiratory intensive care unit due to severe exacerbations. To rule out other possible diagnoses, several investigations were performed, such as computed tomography scan of the chest and neck, fiberoptic laryngoscopy, antineutrophil cytoplasmic antibodies, and complete blood cell count. The patient was first treated with omalizumab, which was completely ineffective, and then with bronchial thermoplasty (BT), again without clinical benefit. The situation remained critical for about 3 months during the last hospitalization, but in February 2017, the Italian Medicines Agency approved the treatment of severe refractory eosinophilic asthma with mepolizumab (Nucala®). Given a blood eosinophil count of 300 cells/μL, our patient was started on 100 mg mepolizumab treatment. After the second administration, symptoms improved progressively, with a reduction in the number and severity of exacerbations, so the patient could finally be discharged from hospital. At follow-up, it was possible to reduce and then suspend oral corticosteroids by continuing only with inhaled corticosteroids/long-acting beta-agonists and montelukast. No further asthmatic exacerbations occurred; symptom control and quality of life improved significantly. To our knowledge, this is the first case of a patient unresponsive to omalizumab and BT but with excellent clinical response to mepolizumab. She is also the first patient to be treated with an anti-IL5 agent in Italy in a real-life clinical setting. The availability of new effective biological agents will allow many patients to resume as normal a life as possible, with a positive outcome also from a social and economic point of view.