Abstract: AIM:To explore the clinical value of serum neopterin (Npt) in assessing coronary artery lesions in patients with acute coronary syndrome (ACS). METHODS: One hundred and twentysix patients with ACS confirmed by coronary angiography (CAG) were divided into STsegment elevation myocardial infarction (STEMI) group (n=45), nonSTsegment elevation myocardial infarction (NSTEMI) group (n=40) and unstable angina pectoris (UAP) group (n=41). Serum levels of Npt, IL8 and hsCRP were detected by enzymelinked immunosorbent assay (ELISA) and were compared among the three groups. The relationship between neopterin and types of coronary artery lesions and plaques was analyzed. RESULTS: Serum level of Npt in STEMI group was obviously higher than in the NSTEMI and UAP groups (P<005), but no significant differences were found in the serum levels of IL8 and hsCRP among the three groups. Serum level of Npt in complex coronary lesions was obviously higher than in simple coronary lesions and borderline coronary lesions (P<005), but no significant differences were observed in the serum levels of IL8 and hsCRP among the three types of coronary lesions. The serum level of Npt in type I and II plaques was obviously higher than in type III plaques (P<005), but there were no significant differences in serum levels of IL8 and hsCRP in the three types of coronary plaques. CONCLUSION: Neopterin can be used to effectively evaluate coronary artery lesions in patients with ACS.