Domiciliary treatment with terbutaline by wet nebulisation (5 mg, four times daily) was compared with placebo in a double-blind study over four consecutive periods, each of seven days duration, in eight patients with severe airflow limitation due to chronic bronchitis and emphysema. Lung function tests performed at the conclusion of each treatment period showed small but significant improvements in FEV1 before and after 500 micrograms of terbutaline by metered dose inhaler (MDI), with reductions in functional residual capacity and residual volume for terbutaline compared with placebo. Morning and evening peak expiratory flow rate recordings were greater and there was a significant reduction in the use of terbutaline by MDI during the terbutaline treatment. Three patients were unable to complete the placebo treatment because of excessive symptoms. Analysing all individual results, only one patient appeared not to benefit from nebulised terbutaline, while the preference rating for the other seven patients was significantly in favour of terbutaline.