Omalizumab (Xolair((R))) is a humanized monoclonal antibody designed to bind specifically to immunoglobulin (Ig)E. It is indicated in the United States for the treatment of adolescent and adult patients (>= 12 yr) with moderate-to-severe persistent asthma who have a positive skin test or in vitro reactivity to a perennial aeroallergen, and whose symptoms are inadequately controlled with inhaled corticosteroids. Omalizumab was evaluated in an extensive clinical development program that included 12 controlled phase IIB/III clinical trials with more than 5243 patients who were appropriate for inclusion in the safety analysis (all ages in all controlled studies). In these studies, omalizumab had an adverse event profile comparable to that of the control group (i.e., placebo or standard therapy). Data presented in this article supports omalizumab as a safe and well-tolerated agent for the treatment of IgE-mediated asthma.