Although percutaneous transluminal coronary angioplasty (PTCA) is being widely performed in patients with multivessel disease, the eventual role it will play will depend on several factors, including the immediate and long-term results, procedural risks and restenosis. An important consideration is that of completeness of revascularization. This is based on cardiac surgical experience, which has documented that if revascularization is complete, the clinical outcome will be improved. The importance of this concept has been borne out in practice. Although complete revascularization is ideal, it cannot be achieved in a substantial number of patients with multivessel disease because of the presence of old total occlusion that cannot be dilated, diffuse and distal disease or a planned dilation strategy. However, many patients with successful dilation but incomplete revascularization do well. In these patients, attempts are made to identify and then dilate a "culprit" lesion. Dilation of these most physiologically important stenoses often results in an excellent short-term outcome. Currently, 2 studies have been initiated to compare the role of PTCA with that of coronary artery bypass grafting for the treatment of patients with multivessel disease. For these studies, initial success and long-term outcome in terms of morbidity and mortality as well as cost considerations will be assessed. The results of these studies will help to put into perspective the complementary roles of PTCA and coronary artery bypass grafting.