The management of severe aortic regurgitation (AR) in patients with reduced left ventricular function and extreme left ventricular dilatation presents a therapeutic dilemma. This study aims to assess risk factors of aortic valve replacement (AVR) for these particular population based on its performances. Two hundred twelve severe AR patients accompanied by left ventricular ejection fraction (LVEF) <50% and left ventricular end-diastolic dimension (LVEDD) 70 mm who underwent isolated AVR between January 2007 and December 2016 were identified retrospectively. Logistic regression and receiver operating characteristic were used to analyze prognostic indicators for in-hospital mortality while Kaplan-Meier analysis for long-term survival. Mean age was 56 13 years with mean LVEF 40 7% and LVEDD 78 6 mm. In-hospital mortality rate was 7%, and survival rates at 5 and 10 years were 88 4% and 73 10%, respectively. Logistic regression analysis indicated in-hospital mortality was associated with preoperative age and LVEF. Receiver operating characteristic analysis showed LVEF=35% was the best cut-off value at which to predict in-hospital death. Kaplan-Meier analysis revealed patients with markedly reduced LV function (LVEF <35%) had lower survival rates compared with other patients with moderate LV dysfunction (LVEF 36% to 50%) (1-, 5-, and 10-year: 90 4%, 64 7%, and 55 14%, vs 97 1%, 94 3%, and 76 7%, p <0.001). An age-matched analysis showed similar trend (p=0.020). In Conclusion, AVR may be unsafe for severe AR patients with markedly reduced LV function (LVEF <35%) and extreme left ventricular dilatation (LVEDD >70 mm) due to poor postoperative early- and long-term outcomes.