Objective: To determine the incidence and risk factors for neurological events complicating cardiac surgery, and the implications for operative outcome in octogenarians. Methods: Of 6791 who underwent primary on-pump CABG and/or valve surgery from 1998 through 2006, 383 were aged >= 80 years. Neurological complications, classified as reversible or permanent, were investigated by head CT scan in patients who did not recover soon after an event. Results: There were more females (47% vs 26%, p < 0.0001) among octogenarians (n = 383, median age 82 years) than among younger patients (n = 6408, median age 66 years). Controlled heart failure, NYHA class III/IV and chronic obstructive pulmonary disease were more prevalent in octogenarians while preoperative myocardial infarction was predominant in younger patients. Octogenarians were at higher operative risk (median EuroScore 6 vs 2, p < 0.0001). Operative procedures differed between octogenarians and younger patients (p < 0.0001); respective frequencies were 45% vs 77% for CABG, 26% vs 10% for AVR, and 23% vs 6% for AVR + CABG. Mortality was higher for octogenarians (8.9% vs 2.1, p < 0.0001). Early neurological complications observed in 3.9% of the entire study population were mostly reversible (3.2%). Age >= 80 years (odds ratio [OR] 2.82, 95% confidence interval [CI] 1.89-4.21, p < 0.0001), prior cerebrovascular disease (OR 2.23, 95% CI 1.56-3.18, p < 0.0001), AVR + CABG (OR 2.92, 95% CI 1.60-5.33, p < 0.0001) and MVR + CABG (OR 4.77, 95% CI 2.10-10.85, p < 0.0001) were predictive of neurological complications. More octogenarians experienced neurological events (p < 0.0001): overall 12.8% vs 3.4%, reversible 11.5% vs 2.8%, permanent 1.3% vs 0.6%. Among octogenarians, neurological complication was associated with elevated operative mortality (18% vs 8% for those without neurological complication, p = 0.03), and prolonged ventilation, intensive care stay and hospitalisation. Predictors of neurological complications in octogenarians were blood and/or blood product transfusion (OR 3.60, 95% CI 1.56-8.32, p = 0.003) and NYHA class III/IV (OR 7.6, 95% CI 1.47-39.70, p = 0.02). Conclusion: Octogenarians undergoing on-pump CABG and/or valve repair/replacement are at higher risk of neurological dysfunction, from which the majority recover fully. The adverse implications for operative mortality and morbidity, however, are profound. Blood product transfusion which has a powerful correlation with neurological complication should be reduced by rigorous haemostasis with parsimonious use of sealants when appropriate. (C) 2008 European Association for Cardio-Thoracic Surgery. Published by Elsevier B.V. All rights reserved.