Objective: To preliminarily investigate the correlation between coronary plaque type and acute coronary syndrome (ACS) using 320-slice volume computed tomography (CT). Methods: Fifty-seven patients who were suspected of having ACS and underwent CT within 30 days of onset were included in this retrospective analysis. All patients underwent 320-slice volume CT coronary image examination and were divided into four groups according to the coronary plaque components: Type I, fully calcified plaque; Type II, mixed plaque (calcification > 50%); Type III, mixed plaque (non-calcification > 50%); Type IV, non-calcified plaque. Results: Coronary plaques were found in 53/57 patients (93%). Of these, 16 (30.2%) had type I, nine (17.0%) had type II, 15 (28.3%) had type III and 13 (24.5%) had type IV plaques, respectively. The presence of Type II-IV non-calcified plaques was significantly associated with ACS (17/53, 32.1%, p<0.001). Type III mixed plaques were also significantly associated with ACS (p<0.05) whereas type II mixed plaques and type IV non-calcified plaques were not significantly associated with ACS (p>0.05). Conclusion: 320-slice volume CT coronary image can clearly depict the components of coronary plaque. Mixed plaques with non-calcified component > 50% are significantly associated with ACS. ? 2011 IEEE.