Several clinical studies highlight the intimate relationship between allergic rhinitis and asthma. For example, a recent analysis of the Asthma Outcomes Registry*found that patients who have both allergic rhinitis and asthma endure more severe symptoms than those with asthma alone. Economic analyses presented during the World Asthma Meeting [Barcelona, Spain; December 1998] now suggest that concurrent allergic rhinitis drives up the cost of managing asthma. These studies prepare the ground for future evaluations into whether jointly managing diseases of the upper and lower airway with oral leukotriene antagonists reduces asthma management costs.