Objective: This study identifies high-risk octogenarians for surgical aortic valve replacement (AVR) because with the current advances in transcatheter valve therapy, a definition of patient selection criteria is essential. Methods: Between 1996 and 2006, 493 consecutive octogenarians with symptomatic aortic stenosis underwent AVR with and without (51%) concomitant coronary artery bypass grafting (CABG). To identify high-risk patient groups, risk factors of 6-month mortality were determined using multivariable logistic regression. Results: The 30-day mortality rate was 8.4% and it increased up to 15.2% until 6 months after AVR. Independent risk factors of 6-month mortality were patients older than 84 years (odds ratio (OR): 2.2 (1.29-3.61)), left ventricular ejection fraction <60% (OR: 2.5 (1.35-4.61)), body mass index (BMI) <24 (OR: 2.0 (1.22-3.36)), creatinine (OR: 1.6 (1.04-2.53)) and blood glucose (OR: 1.01 (1.001-1.009)). High-risk groups were patients older than 84 years with an ejection fraction <60% (6-month mortality 28%) and patients younger than 84 years with an ejection fraction <60% and a BMI <24 (6-month mortality 23.2%). These high-risk groups comprised 37% of the patient population. After isolated AVR, the 30-day mortality and survival at 1 and 5 years was 11.6%, 69% and 35% in this high-risk group, respectively. In octogenarians with an STS score >10 and an EuroScore >20, the 30-day mortality and survival at 1 year was 10.5% and 80%, 11.6% and 77%, respectively. Conclusions: In most octogenarians, AVR is a safe and beneficial procedure. In high-risk octogenarians, identified by STS score >10, EuroScore >20 and by simple three risk factors (age >84 years, ejection fraction <60% and BMI <24), the mortality after surgical AVR was no different from the currently reported outcome after transcatheter AVI. (C) 2009 European Association for Cardio-Thoracic Surgery. Published by Elsevier B.V. All rights reserved.