Patient compliance with an inhaled corticosteroid may be greater if it is combined with a beta-agonist. This study compared compliance with an inhaled corticosteroid (budesonide), and a short-acting inhaled beta-agonist (terbutaline sulphate), and a Turbuhaler inhaler containing a combination of the two drugs. In an open, multicentre, parallel group study 102 asthmatic patients were randomly divided into two groups, either receiving the two drugs in separate Turbuhalers or combined into one Turbuhaler. A twice daily regimen was prescribed and a preweighed metered-dose inhaler (MDI) of salbutamol was provided for rescue use. Compliance was measured using the Turbuhaler Inhalation Computer (TIC), which recorded the time and date of each inhalation over a 12 week period. Forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) measurements were carried out at week 0, 6 and 12. Results from 72 patients were analysed. The average compliance was 60-70%. Treatment was taken as prescribed on 30-40% of the study days, and over-usage occurred on less than 10% of days. Only 15% of patients took the drugs as prescribed for more than 80% of the days. Compliance was no greater in patients using the combined inhalers. Other ways of improving patient self-management need further investigation.