Background:Studies evaluating long-term (≥5 years) outcome of percutaneous coronary intervention (PCI) compared with coronary artery bypass grafting (CABG) in patients with unprotected left main coronary artery disease (ULMCAD) are still limited, despite concerns for late adverse events after drug-eluting stents implantation.Methods and Results:We identified 1,004 patients with ULMCAD (PCI: n=364, CABG: n=640) among 15,939 patients with first coronary revascularization enrolled in the CREDO-Kyoto PCI/CABG registry cohort-2. The primary outcome measure in the current analysis was a composite of death, myocardial infarction, and stroke (death/MI/stroke). The cumulative 5-year incidence of and the adjusted risk for death/MI/stroke were significantly higher in the PCI group than in the CABG group (34.5% vs. 24.1%, log-rank P<0.001, adjusted hazard ratio (HR): 1.48 [95% confidence interval (CI): 1.07–2.05, P=0.02]). The adjusted risks for all-cause death was not significantly different between the 2 groups. Regarding the stratified analysis by the SYNTAX score, the adjusted risk for death/MI/stroke was not significantly different between the 2 groups in patients with low (<23) or intermediate (23–33) SYNTAX score, whereas it was significantly higher in the PCI group than in the CABG group in patients with high (≤33) SYNTAX score.Conclusions:CABG as compared with PCI was associated with better long-term outcome in patients with ULMCAD, especially those with high anatomical complexity.