INTRODUCTION: Frailty is a biological syndrome of the elderly characterized by decreased physiological reserve and weakened response to stressors. Most cardiac surgical risk models incorporate chronologic age as a risk parameter, but not frailty. We aimed to identify the frailty assessment tool with the highest prognostic value to predict postoperative adverse outcomes in elderly patients undergoing cardiac surgery and to investigate whether addition of a frailty parameter to cardiac surgical risk models would increase predictive power. METHODS: This is a single-center, prospective, observational study. Consecutive adults, undergoing elective cardiac surgery between January and May 2020, were included. The European System for Cardiac Operative Risk Evaluation II (EuroSCORE II) and Society of Thoracic Surgeons risk scores were calculated. Fried Scale, Short Physical Performance Battery, Clinical Frailty Scale, and serum albumin were used for frailty assessment. Patients were followed-up for 30 days postoperatively or until discharge. Primary endpoint was a composite of mortality and major morbidity. RESULTS: One hundred sixty-four patients were included (34.76% women, median age 70 years [interquartile range, 67-74]. EuroSCORE II and albumin were the only tools significantly associated with the primary endpoint (P=0.045 and P=0.031, respectively). Model created by combination of EuroSCORE II and albumin was not associated with the primary outcome (P=0.571), however EuroSCORE II's R-squared value increased from 0.07 to 0.144 after addition of albumin. CONCLUSION: Addition of albumin measurement as a frailty marker to EuroSCORE II has the potential to improve EuroSCORE II's ability to predict early postoperative mortality/morbidity in elderly patients undergoing cardiac surgery.