Omalizumab is a humanized monoclonal antibody that is directed against IgE. It has been shown to improve the control of severe allergic asthma in adults and adolescents. Candidates to the treatment are asthmatic patients with positive prick tests and/or in vitro markers of allergy, altered pulmonary function tests, and persistent daytime or nocturnal symptoms despite appropriate treatment with inhaled corticosteroids and long-acting beta-2-agonists.