Rimiterol hydrobromide (Pulmadil) has been shown to have a dose-related bronchodilator effect; the optimum dose by inhalation appears to lie between 200 and 1,000 microgram. When given to a group of asthmatic patients at 'recommended' and 5--10 times 'recommended' dose by aerosol, cardiovascular effects were minimal and of a magnitude similar to that of salbutamol given in the same dosages to the same patients. The very rapid bronchodilator effect of rimiterol would appear to make the drug particularly suitable for the treatment of patients with intermittent asthmatic attacks, before exercise in patients with exercise-induced asthma and for bronchodilatation before using inhaled sodium cromoglycate or corticosteroid aerosols.