The aim of this study was to evaluate the efficacy, safety and preference of pre-school children with regard to two different devices for treatment of bronchial asthma with terbutaline. Turbuhaler, a powder inhaler preloaded with pure terbutaline for inhalation, was compared with a pressurized metered dose inhaler, attached to a Nebuhaler. The study had an open, cross-over randomized design. Each treatment period consisted of 2 weeks. Diary cards were filled in every morning and evening by the parents regarding PEF, asthma symptoms, extra inhalations of terbutaline, and side effects. Twenty-one children (mean age 3.9 years) were included in the study. A highly significant (P less than 0.001) increase in peak expiratory flow (PEF) was obtained after inhalation with both devices. The PEF values in the mornings after inhalation of terbutaline with Turbuhaler were significantly higher (P = 0.046) than those with Nebuhaler. Further, the PEF baseline values in the evenings before inhalation were also significantly higher (P = 0.03) with Turbuhaler. No difference was found in asthma symptoms and extra medication between the two devices. Side effects were mild and few with both devices. The parents found Turbuhaler easier to handle and 19 of 21 preferred this device for future use.