During the years 1977-1980, 47 patients with unstable angina pectoris underwent coronary artery bypass grafting within on an average 16 days after onset of angina. A total of 90 grafts were inserted (1.9 grafts per patient). There were no early deaths in patients operated on for unstable angina. Two late deaths (4.2%) occurred during a follow-up period varying between 14 and 62 months, mean 38 months. Two patients (2.1%) sustained perioperative infarction and two patients (4.2%), late myocardial infarction. All patients were symptomatically improved following operation and 32 (72.7%) are entirely asymptomatic. The authors conclude that patients with unstable angina pectoris can safely undergo early arteriography and semielective operation with results comparable to that for operation in patients with stable angina pectoris.