Allergic bronchopulmonary aspergillosis (ABPA) results from IgE induced pulmonary response to aspergillus species. Recognition and management of ABPA is challenging in cystic fibrosis (CF) patients because changes in symptoms, lung function and chest radiograph are similar to that seen in CF related pulmonary infection. Standard therapy for ABPA includes systemic steroids and adjunctive use of antifungal agents. Little has been published regarding the use of monoclonal anti-IgE antibody in those with ABPA. We report a CF patient with her third exacerbation of ABPA who was treated with monoclonal anti-IgE (omalizumab) antibody; she had unfavorable side effects with prednisone therapy. This therapy resulted in improvement of pulmonary symptoms and lung function not achieved with antibiotics or prednisone alone.