Background: SYNTAX score II (SSII) provides individualized estimates of 4-year mortality after coronary artery bypass grafting (CABG) and percutaneous coronary intervention (PCI) in order to facilitate decision-making between these revascularization methods. The purpose of the present study was to assess SSII in a real-world multicenter registry with distinct regional and epidemiological characteristics. Methods and Results: Long-term mortality was analyzed in 3,896 patients undergoing PCI (n= 2,190) or CABG (n= 1,796) from the Coronary REvascularization Demonstrating Outcome Study in Kyoto (CREDO-Kyoto) PCI/CABG registry cohort-2. SSII discriminated well in both CABG and PCI patient groups (concordance index [c-index], 0.70; 95% CI: 0.68-0.72; and 0.75, 95% CI: 0.72-0.78) surpassing anatomical SYNTAX score (SS; c-index, 0.50; 95% CI: 0.47-0.53; and 0.59, 95% CI: 0.57-0.61). SSII had the best discriminative ability to separate low-, medium-and high-risk tertiles, and calibration plots showed good predictive performance for CABG and PCI groups. Use of anatomical SS as a reference improved the overall reclassification provided by SSII, with a net reclassification index of 0.5 (P< 0.01). Conclusions: SSII has robust prognostic accuracy, both in CABG and in PCI patient groups and, compared with the anatomical SS alone, was more accurate in stratifying patients for late mortality in a real-world complex coronary artery disease Eastern population.