In a placebo controlled study the effects of 6 weeks' treatment with inhaled budesonide (1.6 mg daily) on the impedance of the respiratory system, spirometry and symptom scores were evaluated in 35 patients with chronic bronchitis with forced expiratory volume in one second (FEV1) greater than or equal to 70% predicted. Thirty patients completed the study. No statistically significant differences in the changes in morning peak expiratory flow rate (PEFR), symptom scores, use of terbutaline rescue medication and FEV1 were found between the placebo and the active treatment group. Budesonide treatment was found to result in a small decrease in resonant frequency and a less negative frequency dependence of resistance compared with the placebo group.