The study is a double blind 2x2 factorial study. Patients with coronary disease will be randomly be assigned to L-arginine (9 g/day), creatine 21 g/d, both, or neither dietary supplement. The function of the endothelium will be tested using ultrasound before and after each treatment. These studies will help us understand why the endothelium is abnormal in patients with coronary artery disease and how L-arginine is acting on endothelial function.