Traditionally, practice guidelines have recommended a step-wise approach to treatment based on asthma severity and lung function. However, increasing evidence suggests that asthma may not be adequately controlled in many patients with moderate-to-severe disease despite aggressive therapy, and that regularly evaluating the level of asthma control achieved in individual patients may be more effective than disease severity in guiding treatment decisions. This is reflected in updated asthma guidelines from the National Asthma Education and Prevention Program, which advocate regular assessment of asthma control in terms of the current impairment and future risk associated with the disease. Guideline-recommended options for patients with persistent, moderate-to-severe immunoglobulin E (IgE)-mediated asthma have recently been enhanced by the inclusion of omalizumab. This change is based on growing evidence for the central role of IgE in airway inflammation and asthma and the clinical effectiveness of blocking IgE with omalizumab, a recombinant humanized monoclonal antibody. Omalizumab significantly reduced asthma exacerbations and improved lung function and symptoms in randomized controlled studies of patients inadequately controlled on inhaled corticosteroids plus long-acting beta(2)-agonist therapy; these benefits for reducing asthma impairment and risk were maintained during steroid dose reductions. Omalizumab is well tolerated, although patients should be monitored for possible rare anaphylactic reactions.