Background: It has been shown that pre-procedural C-reactive protein (CRP) could predict late clinical restenosis after stent implantation. However, the relation between pre-procedural CRP and in-stent neointimal hyperplasia (NIH) after successful stent implantation was not clearly demonstrated. Objectives: This study assessed the relation between pre-procedural CRP levels and in-stent NIH after successful stent implantation. Methods: This study included 100 patients who underwent stent implantation for angiographically significant stenosis. Patients were divided into a normal CRP group (< 0.5mg/dL) and elevated CRP group (��� 0.5mg/dL) on the basis of serum CRP levels. All patients underwent angiographic and intravascular ultrasound (IVUS) follow-up at six months. Results: The baseline CRP level was 0.29짹0.08 mg/dL in the normal CRP group and 2.90짹2.31 mg/dL in the elevated CRP group. The levels of fibrinogen and monocyte were higher and the ejection fraction was lower in the elevated CRP group. On coronary angiogram, the complex lesion was observed more frequently in the elevated CRP group. On follow-up angiogram, the late loss was significantly larger in the elevated CRP group (0.54짹0.34 mm vs. 0.95짹0.42 mm, p=0.013). The plaque plus media cross sectional area (P&M CSA) and plaque burden in the minimal lumen CSA at pre-intervention were significantly larger in the elevated CRP group (8.3짹3.2mm2 vs. 11.5짹3.1mm2, 66.2짹7.7% vs. 72.1짹6.6%, p<0.001, =0.032, respectively). The NIH CSA in the minimal lumen CSA at follow-up was significantly larger in the elevated CRP group (1.9짹1.3mm2 vs. 3.0짹1.5mm2, p=0.001). A significant positive correlation was found between pre-interventional CRP levels and pre-interventional P&M CSA and follow-up NIH area (r=0.37, p<0.001, r=0.52, p<0.001, respectively). Conclusion: Elevated CRP may be related to the development of NIH after stent implantation and measuring pre-interventional CRP may be helpful to predict in-stent restenosis after stent implantation.