Achieving control of asthma is a major goal of asthma management. Overreliance on high doses of a beta-agonist or a recent increase in beta-agonist requirement, increasing or wide variability in peak expiratory flow (PEF), and increased frequency of nocturnal symptoms are indicators of poor or declining asthma control, which should highlight the need to take action to avoid the risk of severe and potentially life-threatening asthma exacerbations. The prevention of exacerbations is important because these often require unscheduled physician visits and involve costly medical care. If control is not achieved, diagnosis, treatment, and compliance with therapy should be reviewed, stepping up to a more powerful treatment only if necessary to control symptoms. Many patients often receive inadequate treatment despite the best intentions of their physician. Incorrect inhaler technique and non-compliance with prescribed inhaled asthma therapy may contribute to treatment failure in 50% of patients and are recognized increasingly as reasons for poor response to treatment. Growing evidence indicates that leukotriene receptor antagonists (LTRAs) are useful as controller agents. As a simple tablet therapy, LTRAs should be considered as an alternative treatment option to inhaled corticosteroids in specific patient groups who are poorly compliant or reluctant to use inhaled corticosteroids. These agents reduce the risk of asthma exacerbations and are associated generally with improved compliance compared with inhaled corticosteroids or cromolyn sodium. Moreover, add-on therapy with LTRAs can provide additional benefits to patients whose asthma is not controlled adequately with existing doses of inhaled corticosteroids, and the complementary benefits obtained with these drugs facilitate the achievement of long-term control without the need for increasing the dose of corticosteroids.