Estimation of visceral adipose tissue is important as it carries high cardiometabolic risk and several methods are available as its surrogate. Epicardial fat thickness (EFT) is a direct measure of visceral fat rather than anthropometric measurements. EFT can be accurately measured by two-dimensional (2D) echocardiography. It tends to be higher in patients with Acute Coronary Syndrome (ACS). The present study was intended to find out the association between echocardiographic EFT and severity of Coronary Artery Disease (CAD) in patients with ACS. This cross-sectional observational study was carried out in the department of cardiology, National Institute of Cardiovascular Diseases, Dhaka, Bangladesh from October 2017 to September 2018. Sampling technique was purposive sampling. Comparison between groups was done by unpaired-t test & dichotomous variables were compared by chi-square test. A total of 164 patients was enrolled in the study, prospectively examined EFT on echocardiography and patients were divided into 2 groups, Group I patients with EFT >4.65mm and Group II patients with EFT ≤4.65mm. Coronary angiograms were analyzed for the extent and severity of CAD using Gensini score. The mean EFT (mm) was found 6.1±1.0 in Group I and 3.5±0.7 in Group II (p<0.001). Patients with a higher EFT were associated with a high Gensini score (Group I vs. Group II, 50.3±24.1 vs. 21.9±20.0; p<0.001). Multivariate analysis showed that EFT (OR 6.07, p<0.001) and smoking (OR 2.66, p=0.03) were independent factors affecting significant coronary artery stenosis. By ROC curve analysis, EFT >4.65mm predicated the presence of significant coronary stenosis by 76.1% sensitivity and 69.9% specificity. EFT measured using Transthoracic echocardiography (TTE) significantly correlates with the severity of CAD. It is sensitive, easily available, and cost-effective and assists in the risk stratification and may be an additional marker on classical risk factors for CAD.