Background: Allergic bronchopulmonary aspergillosis (ABPA) in cystic fibrosis (CF) is characterized by destructive changes in the airways. Long-term treatment with oral corticosteroids is often required for repeated exacerbations. Because elevated total IgE is a cardinal abnormality of ABPA, omalizumab has been used sporadically to decrease corticosteroid dose or totally replace corticosteroids. Objective: The aim of this report is to describe our experience with omalizumab treatment in patients with CF and ABPA. Methods: We conducted a review of 6 CF patients with ABPA receiving omalizumab. All patients were treated with oral prednisolone and itraconazole. Omalizumab was started if the patient was not responding to steroid treatment, which was determined according to serum IgE levels and/or clinical findings or depending on if there were side effects caused by steroid treatment. Results: The mean age of patients at the beginning of omalizumab treatment was 16.1 years. One patient had a new diagnosis of ABPA; however, the others had the first to third exacerbation when treated with omalizumab. The mean duration of ABPA by the time that treatment with omalizumab started was 13 +/- 12.4 months (range = 2-29 months). With omalizumab treatment, IgE levels were decreased in all patients, and Aspergillus-specific IgE levels were decreased in 4 patients; however, FEV1(% predicted) improved only in 2 patients who had mild disease. Corticosteroids were reduced in the first, second, and third months of omalizumab treatment in 2, 1, and 3 patients, respectively. In 2 patients, steroid treatment was stopped. None of the patients suffered from side effects of omalizumab. The mean duration of omalizumab treatment was 12.5 months (range = 6-18 months). Conclusions: This study showed steroid-sparing effect, decreasing IgE levels, and improvement in respiratory symptoms in 6 CF patients with omalizumab treatment. Although this is a small sample of the population, omalizumab may be an alternative therapy for ABPA in CF patients who fail to respond to systemic corticosteroids or have serious adverse effects.