Omalizumab is approved for the treatment of severe allergic asthma. To compare the efficacy of omalizumab therapy in patients 50 years or older with patients younger than 50 years. Between November 2005 and November 2007 a total of 174 asthma patients 50 years or older (40.7% male, 51.1% taking oral corticosteroids, and mean [SD] serum IgE level of 315 [353] U/L) and 297 asthma patients younger than 50 years (40.0% male, 50.5% taking oral corticosteroids, and mean [SD] serum IgE level of 363 [431] U/L) who met the European Union criteria for add-on therapy with anti-IgE were treated prospectively with omalizumab for 4 months as part of 2 postmarketing surveillance trials. Compared with the pretrial period omalizumab treatment reduced the rate of severe exacerbations in patients 50 years or older by 68.9% (P < .001) and in patients younger than 50 years by 75.4% (P < .001). After 4 months there was a marked reduction of daily asthma symptoms and nocturnal awakenings by 67.8% and 72.6% in the older and by 79.3% and 82.5% in the younger patients, respectively (P < .001, all 4 comparisons). In 60% of patients 50 years or older lung function improved compared with 69% of patients younger than 50 years. Efficacy of omalizumab was rated as excellent or good by most physicians in patients 50 years or older (68.4%) and younger than 50 years (76.8%, P = .05 elderly vs younger). Adverse events were reported in 35.5% of patients 50 years or older and 32.1% of patients younger than 50 years. There was a higher rate of discontinuation of omalizumab therapy in older patients (20.9% vs 11.1%, P = .006). The present study confirms the clinical efficacy of omalizumab in patients with severe allergic asthma irrespective of age in a real-life setting outside the omalizumab trial program.