The purpose of this study is to evaluate the efficacy of percutaneous transluminal coronary angioplasty in various subgroups of patients with coronary artery disease. At present, over 200 patients have undergone this procedure. It has been demonstrated that the majority of patients with single discrete lesions in one vessel will have a successful procedure and maintain the success for as long as three years. The complication rate is low. We are presently examining the cause of a relatively high restenosis rate, the benefits of the procedure in patients with triple vessel disease, and the duration of the anatomical and clinical improvement achieved.