At the Texas Heart Institute between October 1969 and August 1983, there were 191 single bypass procedures performed without pump oxygenator support. These cases have been divided into two groups: Group I (160 patients) represents the time period from October 1969 through December 1981 and includes our experience with single vessel left anterior descending (LAD) coronary artery bypass without pump oxygenator support; Group II (31 patients) represents the period between January 1982 and August 1983 and includes our initial operative experience in patients with failed percutaneous transluminal coronary angioplasty (PTCA). Of 145 primary operations in Group I patients, 113 were single bypasses to the right coronary artery with a postoperative infarction rate of 3.5% (4/113). Single bypass to the left anterior descending (LAD) coronary artery in 32 patients who underwent operation early in the series was associated with a postoperative infarction rate of 18.7% (6/32) and is no longer performed without pump oxygenator support. Fifteen patients had previous coronary bypass operations and underwent single bypass without pump as a second procedure. Postoperative infarction rate in this redo group was 6.6% (1/15). Long-term follow-up data was obtained on all patients from 1 to 11 years after surgery (mean follow-up, 4 years). Four late cardiac deaths occurred at 2,3,4 and 7 years in the primary operation group (3.5%) 4/113. One late death occurred at 7 years in the redo group (6.6%) 1/15. In Group II, failed PTCA accounted for 39% of the 31 patients who underwent single right bypass without pump support; there were no perioperative infarctions and one death. Coronary bypass can be safely and effectively employed without pump oxygenator support if performed expeditiously and limited to right coronary lesions which have an adequate distal vessel. This technique has become more useful with the advent of attempted PTCA for single coronary lesions.