A double-blind crossover trial compared equal doses of nebulized salbutamol delivered with and without intermittent positive pressure breathing (IPPB) in 20 patients admitted to hospital with life-threatening asthma. No significant differences were observed between the two forms of treatment. It was concluded that the use of IPPB to administer nebulized salbutamol in oxygen had no advantage over passive inhalation in the initial treatment of patients with severe acute asthma.