Aim To explore whether there is relationship among the inflammation markers, acute coronary syndrome (ACS) and carotid atherosclerotic plaque. Methods 92 patients with ACS, 97 patients with stable angina pectoris (SAP) who underwent coronary angiography were enrolled in our study, 40 healthy people were selected as control. The bilateral carotid ultrasounding by high sensitive was investigated to measure the intima-media thickness (IMT), the number of the carotid plaques and the characteristics of the plaques, the serum levels of intercellular adhesion molecular-1 (ICAM-1), matrix metalloproteinase-9 (MMP-9) and high sensitive C-reaction protein (hs-CRP) were determined and the Logistic statistic analysis was used to study the relationship of the inflammatory markers and the unstable plaque. Results The levels of MMP-9, ICAM-1 and hs-CRP in the patients with ACS were significantly higher than those of the patients with SAP and the normal people. According to the Logistic analysis, the results indicated that serum MMP-9, ICAM-1 and hs-CRP were related to the unstable plaque (MMP-9>300 μg/L, OR: 3.12, 95%CI: 1.11～8.98, P=0.027; ICAM-1>200 μg/L, OR: 4.78, 95%CI: 1.34～9.89, P=0.010; hs-CRP >4.0 mg/L, OR: 5.37, 95%CI: 1.43～15.21, P=0.003). Conclusion The numbers of the complex carotid plaques in patients with ACS were significantly higher than those of the patients with SAP and normal control people. There was significant relationship between the complex carotid plaques and ACS.