Asthma is a chronic inflammatory airways disease. The inflammatory process is in many patients driven by an immunoglobulin E (IgE)-dependent process. Patients with severe asthma are at high risk of serious exacerbations and death and have few therapeutic options available. Omalizumab is a humanized monoclonal antibody that acts by binding to and inhibiting the effects of IgE, thereby interfering with one aspect of the asthma cascade. In addition to decreasing exacerbations, it has a steroid sparing role and many beneficial effects in asthma. As suggested by the new asthma GINA 2006 guidelines, this biological agent is indicated in severe persistent allergic asthma.