We evaluated the tolerance of heart transplant recipients to acute betablockade during maximal dynamic exercise. Although the increase in rate and systolic blood pressure were attenuated, exercise tolerance was reduced by only about 15%, which is similar to that previously reported in normal individuals. Betablockade attenuated the increases in heart rate of the denervated donor hearts to a greater extent compared to the increases in the innervated recipient hearts in patients with heterotopic heart transplantation. Therefore, betablockers may be safely used in heart transplantation for appropriate indications such as hypertension.