Background: Several non-traditional factors are associated with increased risk of atherosclerosis among patients with acute coronary syndrome (ACS). Objective: This study aimed to detect predictors for the premature atherosclerosis in patients less or equal than 45 years old in men and less than 55 years old in female and severity of premature atherosclerosis in acute coronary syndrome. Patients and methods: This cross-sectional study included 105 patients with acute coronary syndrome attended for angiography at Cardiology Department, Zagazig University Hospitals. Patients were divided equally into: Group (I) included young patient having traditional risk factors only with acute coronary syndrome, group (II) included young patients having nontraditional risk factors only such as Apo A-I and Apo B and increased lymphocyte to monocyte ratio with acute coronary syndrome and group (III) that included young patient having both traditional and nontraditional risk factors such as ApoA-I, m Apo B and increased lymphocyte to monocyte ratio with acute coronary syndrome. In all groups severity of atherosclerosis was assessed by Gensini score system. Results: About 2/3 of acute coronary syndrome with traditional risk factors group (62.9%) had severe atherosclerosis, with high statistically significant difference between the 3 groups. Hypertension was the only significant traditional factor in relation to severity of atherosclerosis. Also, obese patients had severe atherosclerosis 5 times more than nonobese. Odds of having severe atherosclerosis was 2.66 times more among males than females. Conclusion: A variety of significant non-traditional risk factors place patients at higher risk for ACS. We recommend taking these factors in consideration as regards assessment of occurrence and severity of premature atherosclerosis and ACS.