Despite its association with cardioembolic stroke, atrial fibrillation (AF) appears to be inconsistent as a risk factor for postoperative strokes in patients who underwent cardiac surgery. Furthermore, the relation between AF and the CHA₂DS₂VASc score has not been definitively established with respect to postoperative stroke. We retrospectively analyzed the records of all cardiac surgery performed at our institution between January 2008 and July 2013. Baseline characteristics, operative data, and postoperative outcomes were compared in patients who developed stroke with those who did not. Previously recognized stroke risk factors, including AF, were analyzed along with the CHADS₂ and CHA₂DS₂VASc scores. A total of 3,492 consecutive patients were identified, of which 2,077 (60%) underwent valve surgery, 915 (26%) had coronary artery bypass grafting, 399 (11%) underwent combined coronary artery bypass grafting and valve procedures, and 101 (3%) had other cardiac operations. Postoperative ischemic strokes occurred in 44 patients (1.2%). The development of a stroke was associated with older age (74 ± 12 vs 69 ± 12, p = 0.008), preoperative antiplatelet medication use (38.6% vs 24.5%, p = 0.043), congestive heart failure (37% vs 20%, p = 0.002), and greater CHADS₂ (2.48 ± 1.3 vs 1.98 ± 1.1, p = 0.015) and CHA₂DS₂VASc scores (4.2 ± 1.8 vs 3.4 ± 1.6, p = 0.002). Multivariable analysis demonstrated that the CHA₂DS₂VASc score was the only independent predictor of postoperative strokes (odds ratio 1.25; 95% confidence interval 1.05 to 1.5, p = 0.014). In conclusion, the CHA₂DS₂VASc score appears to predict postoperative strokes independent of the presence of AF.