Turbuhaler is a ready-loaded multiple dose inhaler which does not require co-ordination between release of dose and inhalation. 57 children with asthma participated in this clinical trial to compare the clinical effect and acceptance of terbutaline sulphate via Turbuhaler with that of metered dose inhaler (MDI). The trial consisted of two parts. In the first part of the study, which made use of a double-blind cross-over design, the clinical effect and number of treatment occasions with Turbuhaler were compared with those of MDI. In the second part, which was open, all patients were treated with Turbuhaler for 2 weeks. At the end of this period the patients were asked to make a subjective assessment of effect and to state their preference. There was no difference in clinical effect and number of treatment occasions between Turbuhaler and MDI. A majority of the patients thought Turbuhaler had the best effect and was easy to use.