Twenty-one adult asthmatic patients participated in a trial to compare the clinical equivalence of a single dose of salbutamol inhaled either from a novel multiple dose powder inhaler (MDPI), Easyhaler, or from a conventional metered dose inhaler (MDI). The trial was carried out as a randomized, double-blind, crossover study. The study involved 2 study days with a 6-hour follow-up period of spirometric indices. In addition, blood pressure and heart rate were measured immediately before each lung function test. Our data indicate that salbutamol treatment with the MDPI achieves values which are equivalent to those achieved with the conventional pressurized MDI as regards improving pulmonary function and tolerability. The mean maximum forced expiratory volume in 1 s (FEV1) after the powder dose was 2.44 +/- 0.96 liters and after the aerosol dose 2.45 +/- 0.93 liters. The mean area under the curve of absolute FEV1 values was 822 +/- 340 and 829 +/- 335, respectively. The mean percent change from the baseline in FEV1, forced vital capacity and peak expiratory flow following administration of the preparations was of equal magnitude in both cases. The treatments tested had no effect on blood pressure or heart rate and were well tolerated. A further important finding was that most patients found the MDPI easier or no more difficult to use than the conventional MDI and this probably facilitates the transition from pressurized MDIs to the novel MDPI.