Allergic bronchopulmonary aspergillosis (ABPA) occurs in 7-9% of patients with cystic fibrosis (CF) and causes a worsening of lung function and respiratory symptoms. Standard treatment of ABPA consists of oral steroids; however, higher corticosteroid therapy associated to antifungal agent (itraconazole) long-term treatments are often required to reduce respiratory exacerbations and to prevent progressive lung damage. Here we describe the case of a girl with CF who experienced clinical and functional improvement over 12-months treatment with omalizumab. At birth, our patient was diagnosed with mild-to-moderate CF and from childhood she underwent annual cycles of antibiotic and corticosteroid therapies. At 12 years, she presented with a worsening respiratory condition, asthma symptoms and reduced lung function (FEV1 of 78%). Blood tests showed an increased concentration of plasma total IgE and positive specific IgE antibodies to Aspergillus fumigatus; allergic skin tests were also positive for A. fumigatus. The patient started steroid therapy but had impaired glucose tolerance due to long-term steroid use. Subcutaneous omalizumab 300 mg every two weeks was initiated and after 14 weeks she had improved respiratory symptoms (FEV1 99%) and a marked reduction in the use of systemic antibiotic and corticosteroid therapies. No side effects were reported. Our case shows that therapy with omalizumab for a prolonged period can resolve symptoms of asthma.