Abstract Aims The aim of this study is to investigate the independent determinants of survival in patients with moderate aortic stenosis (AS), stratified by severity of symptoms and left ventricular ejection fraction (LVEF). Methods and results Patients with a first diagnosis of moderate AS (aortic valve area >1.0 and ≤1.5 cm2) were identified. Patients were stratified by New York Heart Association (NYHA) functional class (NYHA I, NYHA II, or NYHA III–IV) and LVEF (LVEF ≥60%, LVEF 50–59%, or LVEF <50%) at the time of moderate AS diagnosis. The primary endpoint was all-cause mortality, while the secondary endpoint included all-cause mortality and aortic valve replacement. Of 1961 patients with moderate AS (mean age 73 ± 10 years, 51% men), 1108 (57%) patients were in NYHA class I, while 527 (27%) and 326 (17%) patients had symptoms of NYHA class II and III–IV, respectively. Regarding LVEF, 1032 (53%) had LVEF ≥60%, 544 (28%) LVEF 50–59%, and 385 (20%) LVEF <50%. During a median follow-up of 50 (23–82) months, 868 (44%) patients died. On multivariable analysis, NYHA class II [hazard ratio (HR): 1.633; 95% confidence interval (CI): 1.431–1.864; P < 0.001], NYHA class III–IV (HR: 2.084; 95% CI: 1.797–2.417; P < 0.001), LVEF 50–59% (HR: 1.194; 95% CI: 1.013–1.406; P = 0.034), and LVEF <50% (HR: 1.694; 95% CI: 1.417–2.026; P < 0.001) were independently associated with increased mortality. Conclusion Moderate AS is associated with poor long-term survival. Baseline symptom severity and LVEF are associated with worse outcomes in these patients. Patients with low-normal LVEF (<60%) and mild symptoms (NYHA II) already have an increased risk of adverse events.