OBJECTIVE To compare the perioperative release levels of cardiac troponin I (cTnI) between off-pump coronary artery bypass grafting (OPCAB) or conventional coronary artery bypass grafting (CCABG) in an attempt to detect myocardial injury. METHODS Fifty-nine patients with instable angina underwent coronary artery bypass grafting by OPCAB in 34 patients aged (59.15 +/- 1.71) years or CCABG in 25 patients, aged (54.46 +/- 1.81) years. RESULTS Baseline characteristics were similar. The number of grafts was similar (OPCAB, mean 2.90; CCABG, mean 3.2), and no patient died. Postoperative myocardial serum enzyme measures were significantly lower in OPCAB, suggesting less myocardial injury. OPCAB patients did not receive blood transfusion, and had higher hematocrit at discharge. Most of OPCAB patients were extubated in 4 hours. CONCLUSIONS Compared with CCABG, OPCAB may achieve similar outcomes; it reduces transfusion volume and creates less myocardial injury.