Introduction: Ischemic heart disease is the leading cause of death all over the world & acute chest pain is one of the most common presentations in the Emergency Departments all over the world with ACS being the major life threatening culprit. Therefore, it needs to be diagnosed immediately with early risk stratification in the ED to identify those patients who might benefit from early aggressive & invasive treatment strategy. But it is an established fact that ACS presents a difficult challenge for the physicians first in terms of prompt diagnosis and then planning the management strategy accordingly. For this reason, the ability of GRACE Risk Score has been tested in determining the presence MVCAD in patients with ACS to help speed up the decision making in this life threatening situation. Methodology: This study was conducted at the Cardiology Department of Shifa International Hospital, Islamabad. Study design was cross-sectional and the duration of the study was 6 months in which a total of 200 patients were observed by using WHO formula for sample size calculation. Keeping confidence level 95%, prevalence = 42%, margin of error = 7%, sample size was calculated to be at least 195 patients. More over non-probability consecutive sampling technique was used for sample collection. Findings: In this study mean age was 59 years with SD ± 10. 66% patients were male whereas 34% were female. Moreover, amongst these 200 patients (who had a GRACE score of >140), 3.5% patients had normal coronary arteries, 35% patients had single vessel coronary artery disease (SVCAD) and importantly 61.5% patients had multivessel coronary artery disease (MVCAD). Conclusion: GRACE Risk score has significant value for assessing the severity and extent of coronary artery stenosis in patients with acute coronary syndrome. It is not limited to any type of ACS instead covers the whole spectrum as it predicts the presence of multi vessel coronary artery disease in patients with ACS & a high GRACE Risk Score (>140) quite consistently.