Background: Uric acid as an inflammatory marker has been hypothesized as a precursor of atherosclerosis and its role has been evaluated in recent studies. Objectives: In our study we wanted to assess its effect on the severity and extent of coronary artery disease in patients presenting to emergency department with acute coronary syndrome. Methods: In this cross-sectional descriptive study, we enrolled all patients with ACS who attended to Shahid Rajaie Emergency Department from May 2016 to May 2018. All patients were sampled for their laboratory evaluation of serum uric acid and routine other lab tests. Besides, their traditional risk factors and medications were recorded and all patients underwent coronary angiography while their SYNTAX score was measured. Results: Two-hundred and six patients were included in our study in which 153 were male (74.3%) and the rest were female (25.7%). The mean age of all patients was 58.37 ± 10.48. From all traditional CAD risk factors, only hyperlipidemia had a direct relation with hyperuricemia (P value < 0.001). Inverse relation was demonstrated between LVEF and serum uric acid level (correlation coefficient-0.126 and P value = 0.047). Analysis also proved a strong relationship between the number of vessels involved and serum uric acid level and the higher serum uric acid level, the more vessels were involved (in SVD 5.29 ± 1.42 mg/dL, 2VD 5.81 ± 162 mg/dL, 3VD 6.14 ± 1.06 mg/dL and 3VD + LM 6.63 ± 1.70 mg/dL and P value = 0.004). Consequently, there was a significant relation between serum uric acid level and SYNTAX score (hyperuricemia prevalence in patients with SYNTAX score less than 22 was 15.8%, in the group of 22-32 SYNTAX score 28.6% and in patients with more than 32 SYNTAX score was 41.4% with P value = 0.007). Conclusions: Serum uric acid level measurement in patients presenting with acute coronary syndrome is both sensitive and efficient and could help in determining the patients' general probability of atherosclerotic disease.