OBJECTIVE: Postoperative new-onset atrial fibrillation (POAF) commonly occurs after coronary artery bypass graft (CABG) surgery. This study aimed to determine the utility of the preoperative netrin-1 and galectin-3 levels for predicting POAF following CABG surgery, as well as that of postoperative serial measurement for assessing these markers’ patterns of expression. PATIENTS AND METHODS: This prospective cohort study included 50 patients that underwent CABG surgery. The plasma netrin-1 and galectin-3 levels were measured via enzyme-linked immunosorbent assay (ELISA) before surgery (baseline) and at 6, 12, and 24 h after surgery. The patients were divided into two groups according to the occurrence of POAF; the POAF (+) group and the POAF (–) group. RESULTS: In total, 26 patients developed POAF, whereas 24 remained in sinus rhythm. Baseline galectin-3 levels were higher in the POAF (+) group than in the POAF (–) group (30.7 ± 10.1 pg mL-1 and 15.7 ± 3.6 pg mL–1, respectively). The post-CABG surgery galectin-3 level increased in both the POAF (+) and POAF (–) groups at 6 h (46.2 ± 26.3 pg mL-1 and 24.9 ± 5.9 pg mL-1, respectively), 12 h (45.2 ± 24.1 pg mL-1 and 26.6 ± 9.3 pg mL-1, respectively), and 24 h (54.2 ± 33.5 pg mL-1and 28.6 ± 7.7 pg mL-1, respectively). The plasma netrin-1 level did not differ between groups at baseline or at 6, 12, and 24 h post CABG surgery. CONCLUSIONS: Whereas netrin-1 does not appear to have any utility as a marker for the development of POAF in CABG surgery patients, the plasma galectin-3 level has high specificity and sensitivity for predicting POAF following CABG surgery and could be considered a marker for predicting POAF.