BACKGROUND: The relationship between sex differences and clinical outcomes following coronary artery bypass grafting (CABG) has been highlighted in several studies. However, these studies were mostly based on single- or multi-center data, and only a few meta-analyses examined long-term outcomes. To address this limitation, we conducted a nationwide population-based cohort study in Korea. METHODS: A total of 48,206 adult patients who underwent first-time isolated CABG between January 2005 and December 2021 were enrolled. To address potential confounding, propensity score (PS) matching was conducted. The primary outcome was overall mortality. RESULTS: Among the enrolled patients, 12,270 (25.5%) were female. The median age of the overall cohort was 66.0 years (interquartile range [IQR], 59.0-72.0), with female patients (median, 69.0; IQR, 63.0-75.0) being significantly older than male patients (P < 0.001). In the PS-matched cohort, in-hospital mortality did not differ significantly between female and male groups (odds ratio, 1.13; 95% confidence interval [CI], 0.78-1.64). However, the female group was a significant predictor of better overall survival (hazard ratio [HR], 0.83; 95% CI, 0.77-0.90) compared to the male group. Cardiac-related mortality was comparable between the two groups (HR, 0.89; 95% CI, 0.65-1.22). The median duration of the follow-up period was 7.8 (IQR, 4.0-12.6) years. CONCLUSION: In this nationwide population-based PS-matched cohort study, female patients who underwent isolated CABG exhibited significantly lower overall mortality compared to male patients during long-term follow-up, whereas no significant difference was observed in cardiac-related mortality.