Bambuterol tablets, 10 and 20 mg, and terbutaline CR-tablets, 5 and 7.5 mg, have been compared for their capacity to produce subjectively determined tremor in a randomised, double-blind, cross-over study in 40 healthy volunteers. The duration of each treatment was one week, with an intervening washout period of at least 2 weeks. On the second and the last treatment days in each period, tremor was subjectively assessed on six occasions. In addition, an overall assessment of night and day tremor was made each morning and evening. Analyses were made for the second and last treatment days and during the treatment week. Paired comparisons for tremor during daytime showed a significant difference between the treatments, with the exception of bambuterol 20 mg and terbutaline 5 mg. Bambuterol 10 mg caused less tremor and terbutaline 7.5 mg caused more tremor than the other treatments. At the end of the week, the differences were smaller and were only significant when comparing bambuterol 10 mg with the 20 mg dose and with high dose terbutaline. Terbutaline 7.5 mg caused more tremor at night than the other treatments. The tremor experienced was generally mild, and after bambuterol 10 mg it was almost negligible (mean 0.13 after the first dose). Two subjects recorded a score of 3 after terbutaline 7.5 mg. The results indicate that, in doses equipotent with regard to bronchodilation, tremor is less pronounced after bambuterol as compared to controlled release tablets of terbutaline.