The American College of Cardiology/American Heart Association guidelines for exercise testing do not take a position regarding the utility of routine stress testing after coronary artery bypass grafting (CABG). Our purposes were (1) to document the patterns of use of stress testing after CABG and (2) to establish whether the choice of stress testing strategy is associated with clinical characteristics of patients. The Routine versus Selective Exercise Treadmill Testing after Coronary Artery Bypass Graft Surgery (ROSETTA-CABG) Registry is a prospective multicenter study that examined the use of stress testing after CABG among 395 patients at 16 clinical centers in 6 countries. During the 12 months after CABG, 37% of patients underwent stress testing (range across centers 0% to 100%). Among patients who underwent stress testing, 24% had a clinical indication and 76% had it as a routine follow-up. A total of 65% of stress tests involved exercise treadmill testing alone, 17% involved stress nuclear perfusion imaging, 13% involved stress echocardiographic imaging, and 5% involved other types of stress tests, such as positron emission tomographic scans. The first stress test was performed at a median of 13 weeks after CABG, with 20% of patients having second tests at a median of 28 weeks and 6% having additional tests at a median of 34 weeks. Univariate and multivariate analyses demonstrated that the chief determinant of using routine stress testing was the clinical center. In conclusion, these results suggest that there is little consensus on the appropriate use of stress testing soon after CABG. Practice patterns vary widely; poorly diagnostic tests are used routinely; and the clinical center at which the procedure is performed, rather than the clinical characteristics of the patient, determines the use of stress testing after CABG.