Twenty adult patients with stable asthma were treated with cumulatively increasing doses of salbutamol delivered from a metered dose inhaler (MDI) and from a novel multiple dose powder inhaler (MDPI), Easyhaler, in a randomized 3-period crossover study. Four doses of salbutamol (delivered doses to the patient: 90, 90, 180, 360 micrograms; cumulative dose of 720 micrograms) were administered during each of the three study days and were inhaled every 30 minutes. Drug doses were released from the powder inhaler either before or during inhalation. Spirometry was performed at the beginning of each study day and 20 minutes after each dose. The lung function parameters after cumulative dosing of salbutamol were equal during each study day. The maximal percentage changes in forced expiratory volumes in one second after 720 micrograms of salbutamol were 24% with the MDI and 23% and 24% with the Easyhaler inhaler, respectively. Ten patients reported mild side effects when using the MDI, three when the powder was released before inhalation and five when the MDPI was actuated during inhalation. No significant changes in heart rate or blood pressure were observed during the study. We conclude that the novel multiple dose powder inhaler is clinically equally effective and slightly better tolerated than conventional metered dose inhaler when equal doses of salbutamol are inhaled by asthmatic patients.