This randomized, double-blind, double-dummy, parallel group clinical trial compared the efficacy and safety of adding salmeterol xinafoate to concurrent inhaled beclomethasone dipropionate therapy with doubling the dose of beclomethasone dipropionate in patients experiencing symptoms on low-dose beclomethasone. Salmeterol added to low-dose beclomethasone was superior (p < or = 0.05) to doubling the dose of beclomethasone in improving peak expiratory flow (PEF) and forced expiratory volume in 1 sec (FEV1), and in reducing symptoms of asthma, sleep loss, nighttime awakenings, and use of albuterol. Both treatment regimens had comparable safety profiles. In asthma patients inadequately controlled despite the use of low-dose inhaled corticosteroids (i.e., less than 400 microg per day), the addition of salmeterol may be a more effective treatment option than doubling the dose of inhaled corticosteroids.