Objectives: Our objectives were to evaluate short- and long-term mortality associated with new-onset atrial fibrillation after coronary artery bypass grafting and to identify preoperative and intraoperative patient characteristics associated with new-onset atrial fibrillation. Methods: Three independent investigators comprehensively reviewed the literature using Medline from 1960, Web of Science from 1980, and Scopus from 1960. All searches were done through December 2009. Selected cohort studies were used to evaluate associations between new-onset atrial fibrillation after coronary artery bypass grafting or coronary bypass plus valve and short-term mortality (defined as 30-day or in-hospital mortality) and long-term mortality (defined as mortality ≥ 6 months). We excluded studies involving atrial flutter, off-pump coronary bypass, and isolated valve surgery. Heterogeneity among studies was accounted for by meta-analysis with random-effects models. Results: Eleven studies (n = 40,112) met our inclusion criteria. New-onset atrial fibrillation was associated with higher short-term mortality (3.6% vs 1.9%; odds ratio [OR], 2.29; 95% confidence interval [CI], 1.74-3.01; P < .00001; heterogeneity of effects, P = .002). Mortality risks at 1 year and 4 years were 2.56 (95% CI, 2.14-3.08) and 2.19 (95% CI, 1.97-2.45; P < .0001), respectively. Older age, lower ejection fraction, history of hypertension, heart failure, prior stroke, peripheral arterial disease, and longer cardiopulmonary bypass and aortic clamp times were associated with new-onset atrial fibrillation. Preoperative use of ß-blockers reduced occurrence of new-onset atrial fibrillation (OR, 0.94 [95% CI, 0.88-1.01; P = .08]), whereas angiotensin-converting enzyme inhibitors increased it (OR, 1.20 [95% CI, 1.11-1.29], P < .00001). Conclusions: New-onset atrial fibrillation after coronary artery bypass grafting appears to increase short- and long-term mortality. Preoperative use of ß-blockers, avoidance of angiotensin-converting enzyme inhibitors, and shorter cardiopulmonary bypass and aortic clamp times potentially reduce occurrence of new-onset atrial fibrillation.