Smokers with asthma show a reduced response to inhaled corticosteroids. We hypothesized that a peroxisome proliferator-activated receptor-gamma (PPAR-gamma) agonist would be superior for the clinical treatment of these asthma patients. Forty-six smokers with asthma were randomized to inhaled beclometasone dipropionate (200 microg per day) or rosiglitazone (8 mg per day) for 4 weeks. Rosiglitazone produced improvements in lung function (forced expiratory volume in 1 s (FEV(1)) = 183 ml, P = 0.051; forced expiratory flow between 25 and 75% of the forced vital capacity (FEF(25-75)) = 0.24 l/s, P = 0.030) as compared with inhaled beclometasone dipropionate. Further trials using PPAR-gamma agonists in steroid-resistant airway disease are indicated.