OBJECTIVE: This study aimed to investigate the predictive value of the newly defined C-Reactive Protein (CRP)/Albumin Ratio (CAR) in determining the development of atrial fibrillation (AF) in comparison with other inflammatory markers, such as Neutrophil/Lymphocyte (N/L) Ratio and Platelet/Lymphocyte (P/L) Ratio, in patients undergoing Coronary Artery Bypass Grafting (CABG) surgery. METHODS: The population of this observational study consisted of 415 patients undergoing CABG. The study cohort was subdivided into two groups based on the development of AF. Complete blood counts, serum CRP, and serum albumin levels were evaluated before the CABG. The CAR, N/L, and P/L ratios of all the patients were calculated. Predictors of postoperative AF were determined by multiple logistic regression analysis (MLRA). RESULTS: During follow-up, 136 patients (32.8%) developed postoperative AF. With MLRA, independent risk factors for postoperative AF were determined as follows: fasting glucose level (OR: 1.01; 95 % CI: 1.00-1.01, P <0.001), age (OR: 1.12; 95 % CI: 1.07-1.17, P <0.001), left ventricle ejection fraction (OR: 0.90; 95 % CI: 0.87-0.94, P <0.001), male gender (OR: 3.32; 95 % CI: 1.39-7.90, P = 0.007), 24-hour drainage amount (OR: 1.004; 95 % CI: 1.002-1.005, P <0.001), and CAR (OR: 1.82; 95 % CI: 1.53-2.16, P <0.001). Receiver Operating Characteristic curve analysis showed that CAR (C-statistic: 0.75; 95% CI: 0.71-0.79, p< 0.001) was a significant predictor of AF. CONCLUSION: Novel inflammatory marker CAR can be used as a reliable marker to predict the development of AF following CABG.