The objectives of this study were to compare the efficacy and tolerability of twice-daily formoterol dry powder 12 microg and 24 microg (Foradil) delivered via Aerolizer inhaler with four times daily albuterol (salbutamol) 180 microg delivered via metered dose inhaler (MDI) and placebo. A total of 554 adolescents and adults (ages 12-75 years) with mild-to-moderate asthma were randomized to this 12-week, multicenter, double-blind, double-dummy, placebo-controlled, parallel-group study. Twelve-hour spirometry measurements were taken at weeks 0, 4, 8, and 12. A total of 484 patients completed the study (122, 116, 127, and 119 given formoterol 12 microg, formoterol 24 microg, albuterol, and placebo, respectively). For the primary efficacy variable, the forced expiratory volume in 1 second (FEV1), both formoterol 12 microg and 24 microg were statistically superior to placebo at all time points on all test days (p < or = 0.017) and to albuterol at most time points on all test days (p < or = 0.001). The onset of improvement in FEV1 was rapid, with 15% increase within 5 min in 57%, 71%, and 65% of formoterol 12 microg, formoterol 24 microg, and albuterol patients, respectively. Formoterol was also superior to placebo and albuterol in terms of secondary efficacy variables: FEV1 area under the curve, percentage of predicted FEV1, forced vital capacity and forced expiratory flow, asthma symptom scores, and peak expiratory flows. In conclusion, both formoterol doses were superior to placebo in all lung function measurements. Overall, compared with albuterol, both formoterol doses produced superior bronchodilation. Formoterol and albuterol were safe and well-tolerated.