Abstract: AIM: To explore the relationship between chemokines CCL19 and CCL21 and the degree of stenosis of coronary artery in patients with acute coronary syndrome (ACS). METHODS: One hundred and two patients with acute ACS were included in the study. Included were 33 cases with ST-segment elevation myocardial infarction (STEMI), 37 cases with non ST-segment elevation myocardial infarction (NSTEMI), 32 cases with unstable angina, and 36 cases with stable angina (SA). Recruited as controls were 30 patients with chest pain but no ischemic changes in ECG and no coronary heart disease confirmed by coronary angiography. The levels of chemokines CCL19 and CCL21 were measured by ELISA and the severity of coronary artery disease was measured by Gensini scoring system. RESULTS: Serum levels of chemokines CCL19 and CCL21 in patients with ACS were significantly higher than those in control group ［CCL21: (149.33±26.24) ng/L vs.(111.45±22.28) ng/L vs.(108.38±22.28) ng/L, P<0.01］ and ［CCL19: (77.45±16.27) ng/L vs.(54.74±19.44) ng/L vs.(57.38±21.28) ng/L, P<0.01］. No significant difference was observed in Gensini scores among the three groups of ACS patients. The levels of chemokines CCL19 and CCL21 in peripheral blood were not correlated with coronary artery lesions in ACS. CONCLUSION: Levels of CCL19 and CCL21 may reflect the severity of coronary artery disease and play an important role in coronary artery plaque destabilization.