The use of beta-adrenoceptor blocking drugs has been thought to impair physical performance. To test this statement, 12 patients with mild to moderate hypertension performed a submaximal exercise test during treatment with placebo and after 3 and 24 months of monotherapy with betaxolol, 20 to 40 mg daily. The resting heart rate and systolic and diastolic blood pressures were reduced after 3 months of treatment and the reduction was maintained 24 hours after the last dose at the 2-year visit. A 12% to 14% reduction of exercise-induced tachycardia was found, but blood pressure during exercise was reduced only in the patients with mild hypertension. However, in no patient did the working capacity decrease.