To compare 6-month post-percutaneous transluminal coronary angioplasty (PTCA) outcomes and cardiac procedure use among patients with and without prior coronary artery bypass graft (CABG) surgery, we examined 791 patients who were enrolled in the Routine versus Selective Exercise Treadmill Testing after Angioplasty (ROSETTA) Registry. The ROSETTA Registry is a prospective, multicenter registry that examines the use of functional testing after successful PTCA. Most patients were men (76%, mean age 61 ± 11 years) who underwent single-vessel PTCA (85%) with stent implantation (58%). Baseline and procedural characteristics differed between patients with a prior CABG (n = 131) and patients with no prior CABG (n = 660), including Canadian Cardiovascular Society angina class III to IV (60% vs 49%, respectively, p = 0.03) and stenosis involving the proximal left anterior descending coronary artery (10% vs 22%, p = 0.004). Event rates among patients with prior CABG were higher than among patients with no prior CABG, including unstable angina (19% vs 11%, p = 0.02), myocardial infarction (2% vs 1%, p = 0.2), death (4% vs 2%, p = 0.08), and composite clinical events (22% vs 12%, p = 0.003). Furthermore, patients with prior CABG had higher rates of follow-up cardiac procedures, including angiography (24% vs 14%, p = 0.008) and PTCA (13% vs 7%, p = 0.04), but not repeat CABG (2% vs 3%, p = 0.8). A multivariate analysis that included baseline clinical and procedural characteristics demonstrated that prior CABG was a significant independent predictor of clinical events and cardiac procedure use (odds ratio 2.3, 95% confidence interval 1.5 to 3.5, p = 0.0001). Within the prior CABG group, patients with a PTCA of a bypass graft had a higher composite clinical event rate than patients with a PTCA of a native vessel (32% vs 17%, p = 0.05). In contrast, patients with a PTCA of a native vessel had event rates similar to those of patients with no prior CABG (17% vs 12%, p = 0.2). Thus, post-CABG patients have an increased risk of developing a cardiac event or needing a follow-up cardiac procedure during the 6 months after PTCA.