The present study investigated the relation between plasma high-sensitivity C-reactive protein (hs-CRP) and adiponectin and coronary plaque components in patients with acute coronary syndrome (ACS). Previous studies showed a pivotal role of inflammation in the progression of atherosclerosis and the prognostic value of several biomarkers. However, relations among inflammatory biomarkers and plaque characteristics were unknown. Ninety-three culprit plaques (ACS n = 50, non-ACS n = 43) and 56 nonculprit plaques (ACS n = 28, non-ACS n = 28) were analyzed using Virtual Histology intravascular ultrasound to examine relations among plasma hs-CRP, adiponectin, and ratios of each coronary plaque component. Plasma adiponectin was significantly lower and plasma hs-CRP was significantly higher in patients with than without ACS. Culprit plaques in patients with ACS had greater amounts of necrotic core plaque than those in patients without ACS. There was an inverse relation between serum hs-CRP and adiponectin with regard to necrotic core ratio in both culprit and nonculprit lesions in patients with ACS, but not those without ACS. In conclusion, increased plasma hs-CRP and hypoadiponectinemia might be related to the progression of ACS.