Introduction: Little is known about the long-term prognosis of young adults undergoing surgery for acute aortic valve infective endocarditis (IE). The aim of this study was to determine late survival, causes of death and predictors of mortality following surgical treatment in these patients. Methods: From 2000 to 2015, all patients 18-60 years undergoing aortic valve/root replacement for IE in 2 high-volume centers were included. Patients with concomitant endocarditis on other valves were excluded. The primary objective was to determine long-term survival and predictors of mortality. Secondary outcomes were early results and rates of IE recurrence. Mean follow-up was 6 ± 4 years (93% complete). Results: A total of 166 patients (mean age 47±11 years, 81% male) were included: 13% were intravenous drug users and 38% had a root abscess. Streptococcus (31%) and Staphylococcus aureus (21%) were the most common organisms. Different valve substitutes were used: mechanical prosthesis (49%), bioprosthesis (30%), homograft (13%) and Ross procedure (8%). Hospital mortality was 6.6%. The overall rate of IE recurrence was 8.3% and 11.4% of patients needed reintervention on the aortic valve. Actuarial survival at 1, 5 and 10 years was 88%, 80% and 71%, respectively. No significant difference was observed between different valve substitutes. However, late survival was significantly lower than that the age- and sex-matched general population, even after excluding 30-day mortality (Figure). Higher BMI (HR= 1.06, p=0.04), operation time (HR=3.5, p<0.01) and intravenous drug usage (HR= 3.1, p<0.01) were predictors of late mortality. Conclusion: Despite reasonable perioperative outcomes in young adults undergoing surgery for aortic valve endocarditis, long-term mortality and recurrence rates remain high. This suggests that endocarditis is a chronic condition requiring a tailored surgical approach and long-term patient surveillance. [ABSTRACT FROM AUTHOR]