Aortic valve sclerosis (AVS) represents a degenerative process that progresses with advancing age. The study was intended to find out the association between aortic valve sclerosis and the severity of CAD in patient's age ≤65 years with acute coronary syndrome. This cross-sectional analytical study was carried out in the department of cardiology, National Institute of Cardiovascular Diseases (NICVD), Dhaka, Bangladesh during a period of October 2017 to September 2018. A total of 140 Acute coronary syndrome (ACS) patients undergoing coronary angiogram during index hospitalization were included in the study. Study patients were divided into two groups on the basis of echocardiographic presence or absence of Aortic valve sclerosis (AVS), with 70 patients in each group. Group I was patients with aortic valve sclerosis and Group II was patients without aortic valve sclerosis. All patients underwent transthoracic echocardiography before they underwent coronary angiography on different days. Severity of CAD was determined by Gensini score and Vessel score. Association of traditional risk factors (smoking habit, hypertension, diabetes mellitus, dyslipidaemia and family history of CAD) with severity of CAD was investigated. Coronary angiography showed that AVS group had a higher positive rate of CAD (82.9% vs. 54.3%, p<0.001) and incidence rate of triple vessel CAD (40% vs. 14.3%, p<0.001) than non-AVS group. Gensini score had higher in AVS group than non AVS group (37.9±27.8 vs. 12.5±14.2; p<0.001). Multivariate analysis showed that AVS (p=0.01) and age (p=0.04) were independent predictors of the presence of significant coronary artery disease. The study concluded that echocardiographically detected AVS is an independent predictor of coronary artery disease severity. There is positive correlation between severity of AVS and severity of CAD in patient's age ≤65 years with ACS.