The objective of this study was to investigate the effects of 12 weeks of standard cardiac rehabilitation on endothelial function, oxidative stress, and antioxidant defenses in patients with coronary artery disease. Twelve weeks of endurance exercise training led to an improvement in endothelial function as measured by brachial artery flow-mediated dilation (7.9% at baseline vs 11.1% at 12 weeks). Exercise training resulted in increased plasma nitrite and nitrate levels, increased plasma superoxide dismutase activity, and decreased oxidative stress.