The effect of non-selective beta-adrenoceptor blockade on gastrointestinal transit time (GITT) was measured in 20 healthy volunteers with a radiographic method. By means of double-blind, crossover technique, each subject was studied during treatment with 80 mg oral propranolol or placebo twice daily for 7 days. The number of radiopaque markers retained in the alimentary tract did not differ significantly between the placebo and the propranolol periods. The mean GITT for placebo was 78 h and for propranolol 77 h. During propranolol treatment the heart rate and blood pressure were significantly decreased. It is concluded that non-selective beta-adrenoceptor blockade does not influence human gastrointestinal transit time under unstrained conditions.