This is the first study of the inhaled corticosteroid, budesonide, delivered by metered-dose inhaler (BD MDI) using innovative co-suspension delivery technology in adults with asthma.To characterize the effects of BD delivered by MDI on lung function and safety.Randomized, double-blind, 4-week cross-over, placebo-controlled, phase IIb study of adults (18-65 years of age) with mild-to-moderate persistent asthma. The subjects received twice-daily BD MDI 320 μg, 160 μg, and placebo MDI, and either BD MDI 80 μg or 40 μg. The primary endpoint was change from baseline in morning trough forced expiratory volume in 1 second (FEV1) at the end of the treatment period (EOT). Secondary endpoints included change from baseline in morning and evening predose peak expiratory flow rate (PEFR), rescue medication use, and Asthma Control Questionnaire 5-question version (ACQ-5) score. Safety was also assessed.A total of 147 subjects were randomized. All doses of BD MDI improved morning trough FEV1 at EOT, and morning and evening predose PEFR in the last treatment week versus placebo (all p www.clinicaltrials.gov.