In 113 patients demonstrating the clinical syndrome of unstable angina, acute-stage coronary angiography revealed multivessel disease. Acute PTCA of the ischaemia-related coronary artery or bypass grafting was performed depending on angiographic criteria. Of the total of 68 patients in whom PTCA was performed, 45 had two-vessel disease (2 vd) and 23 three-vessel disease (3 vd). 12 of the 45 patients with bypass operation had a left main stem stenosis, whereas 33 had three-vessel disease. The primary success rate of PTCA was 81%, 89% in patients with 2 vd and 70% in patients with 3 vd. Acute post-PTCA bypass grafting was necessary in 2 patients having 2 vd and in 5 patients suffering from 3 vd. 5 of the 68 patients treated with PTCA developed a transmural myocardial infarct and one patient died after PTCA and emergency bypass surgery. 8 of the 45 operated patients had a perioperative or postoperative myocardial infarct and 5 patients died intraoperatively or postoperatively. The overall morbidity was 11.5%, and the mortality of hospitalised patients was 5.3% (6/113). Combination of PTCA with emergency bypass grafting offers a new and effective treatment with an acceptable risk even in multivessel disease patients and in those having unstable angina pectoris. The additional use of PTCA definitely improves therapeutic management in this high-risk population.