In order to investigate the relationship between sympathetic activity and postexercise systolic blood pressure (SBP) and exercise-induced ventricular arrhythmias in patients with coronary artery disease (CAD), we studied 38 patients and 9 normal subjects who underwent treadmill testing. Peak pressure-rate product was similar in the 2 groups. The plasma concentrations of norepinephrine and epinephrine at rest and immediately after exercise were significantly higher in patients with CAD compared with normal subjects (norepinephrine at rest, p < 0.01; norepinephrine immediately after exercise, p < 0.05; epinephrine at rest, p < 0.05; epinephrine immediately after exercise, p < 0.05). The level of norepinephrine immediately after exercise was significantly higher in 15 patients with a postexercise SBP increase than in 23 patients without that SBP change (p < 0.05), whereas the level of epinephrine was similar in the 2 groups. The level of epinephrine immediately after exercise was significantly higher in 10 patients with exercise-induced premature ventricular contractions than in 28 patients without those arrhythmias (p < 0.05), whereas the level of norepinephrine was similar in the 2 groups. We conclude that a postexercise SBP increase is related to the augmentation of sympathoneural activity and that exercise-induced ventricular arrhythmias are related to the augmentation of sympathoadrenal activity.