Backgrounds: Inflammatory marker is associated with poor adverse clinical outcomes in patients undergoing percutaneous coronary intervention (PCI). We sought to evaluate the association between inflammatory marker, high-sensitivity C-reactive protein (hs-CRP), and coronary plaque composition of culprit lesion in patients undergoing PCI. Methods: Virtual histology-intravascular ultrasound (VH-IVUS) examination during PCI was performed in 145 consecutive patients (mean 60 yrs old, 106 males). Study subjects were divided into 2 groups: 72 patients with low hs-CRP ([less than or equal to]1.2mg/dL) and 73 patients with high hs-CRP (>1.2mg/dL). Results: Patients with high hs-CRP were older (mean 63 yrs vs. 57 yrs old, P=0.001), more likely to be female (34.2% vs. 19.4%, P=0.044), and lower prevalence of prior myocardial infarction (2.7% vs. 11.1%, P=0.047), than those with low hs-CRP, whereas there were no significant differences in terms of hypertension, diabetes, smoking, hyperlipidemia, clinical diagnosis, multivessel disease and plaque rupture or calcium on gray scale IVUS between two groups. With regards to VH-IVUS findings over the entire lesion length, patients with high hs-CRP had larger fibrofatty volume (22.7짹25.5mm³ vs. 15.1짹17.2mm³, P=0.036) as well as percent fibrofatty volume (16.1짹10.3% vs. 11.7짹9.2%, p=0.008) than those with low hs-CRP, although lesion length, lumen volume, vessel volume, and fibrous, dense calcified, and necrotic core volume did not show any significant differences. At the minimal lumen site, any VH-IVUS findings did not show significant differences between two groups. Age (beta=0.241, 95% confidence interval (CI) 0.004 to 0.017, P=0.003) and percent composition of fibrofatty volume (beta=0.179, 95% CI 0.001 to 0.017, P=0.027) over the entire lesion length were associated with high inflammatory marker. Conclusions: Inflammatory marker is related with percent fibrofatty volume over the entire lesion length in patients undergoing PCI.