Several risk stratification scores, based on angiographic or clinical parameters, have been developed to evaluate outcomes in patients with left main coronary artery disease (LMCAD) who undergo coronary artery bypass grafting (CABG). This study aims to validate the predictive ability of different risk scoring systems with regard to long-term outcomes after CABG. This single-center study retrospectively re-evaluated the Synergy Between PCI with TAXUS and Cardiac Surgery (SYNTAX) score; EuroSCORE; age, creatinine, and ejection fraction (ACEF) score; modified ACEF score; clinical SYNTAX; logistic clinical SYNTAX score (logistic CSS); and Parsonnet scores for 305 patients with LMCAD who underwent CABG. The endpoints were 5-year rate of all-cause death and major adverse cardio-cerebral events (MACCEs), including cardiovascular (CV) death, myocardial infarction (MI), and stroke and target vessel revascularization (TVR). Compared with the SYNTAX score, other scores were significantly higher in discriminative ability for all-cause death (SYNTAX vs others: P < 0.01). The EuroSCORE ≥6 showed significant outcome difference on all-cause death, CV death, MI, and MACCE (P < .01). Multivariate analysis indicated the SYNTAX score was a non-significant predictor for different outcomes. Adjusted multivariate analysis revealed that the EuroSCORE was the strongest predictor of all-cause death (hazard ratio[HR]: 1.17; P < 0.001), CV death (HR: 1.16; P < 0.001), and MACCE (HR: 1.09; P = 0.01). The ACEF score and logistic CSS were predictive factors for TVR (HR: 0.25, P = 0.03; HR: 0.85, P = 0.01). The EuroSCORE scoring system most accurately predicts all-cause death, CV death, and MACCE over 5 years, whereas low ACEF score and logistic CSS are independently associated with TVR over the 5-year period following CABG in patients with LMCAD undergoing CABG.