Objective To determine if multi-detector CT (MDCT) characterization of plaque is corre-lated with the classification of acute coronary syndrome (ACS). Methods Altogether 1900 patients were examined by MDCT from December 2007 to May 2009, of whom 95 patients fulfilled the criteria of ACS. Those patients were divided into the discrete plaque group (n=61) and diffuse plaque group (n=34) based on the findings in MDCT. The clinical diagnosis of ACS and CT results were analyzed, including segment stenosis score, segment involvement score, 3-vessel plaque score, left main score, calcification score, and re-modeling index. The incidences of major adverse cardiac events in follow-up period were also recorded. Results The patients of the diffuse plaque group were older than those of the discrete plaque group (P<0.0001). The diffuse plaque group presented more cases of hypertension, pe-ripheral artery disease, diabetes, and heart failure than discrete plaque group (all P<0.05). All the 5 patients with ST-segment elevation myocardial infarction were found in discrete plaque group. The segment stenosis score of the discrete plaque group was lower than that of the diffuse plaque group (5.15±3.55 vs. 14.91±5.37, P<0.001). The other four scores demonstrated significant inter-group difference as well (all P<0.05). The remodeling index of the discrete plaque group was higher (1.12±0.16 vs. 0.97±0.20, P<0.05). Follow-up data showed that major adverse cardiac events occurred more frequently in diffuse plaque group than in discrete group (29.41% vs. 11.48%, P=0.0288). Conclusions Characteristics of discrete and diffuse plaques may be significantly different among different classes of ACS. The diffuse plaque may present higher risk, correlated to higher mortality. The diagnosis of discrete and diffuse plaques by MDCT would provide a new insight into the prognosis and treatment of ACS. Objective To determine if multi-detector CT (MDCT) characterization of plaque is corre-lated with the classification of acute coronary syndrome (ACS). Methods Altogether 1900 patients were examined by MDCT from December 2007 to May 2009, of whom 95 patients fulfilled the criteria of ACS. Those patients were divided into discrete plaque groups (n = 61) and diffuse plaque groups (n = 34) based on the findings in MDCT. The clinical diagnosis of ACS and CT results were analyzed, including segment stenosis score, segment incidence score, 3-vessel plaque score, left main score, calcification score, and re-modeling index. The incidences of major adverse cardiac events in follow-up period were also recorded. Results The patients of the diffuse plaque group were older than those of the discrete plaque group (P <0.0001). The diffuse plaque group presented more cases of hypertension, pe-ripheral artery disease, diabetes, and heart failure than discrete plaque group (all P <0.05). All the 5 patients with ST-segment elevation myocardial infarction were found in discrete plaque group. The segment stenosis score of the discrete plaque group was lower than that of the diffuse plaque group (5.15 ± 3.55 vs. 14.91 ± 5.37, P <0.001). The other four The remodeling index of the discrete plaque group was higher (1.12 ± 0.16 vs. 0.97 ± 0.20, P <0.05). Follow-up data showed that major adverse cardiac Events occurred more frequently in diffuse plaque group than in discrete group (29.41% vs. 11.48%, P = 0.0288). Conclusions Characteristics of discrete and diffuse plaques may be significantly different among different classes of ACS. The diffuse plaque may present higher risk, The diagnosis of discrete and diffuse plaques by MDCT would provide a new insight into the prognosis and treatment of ACS.