Objectives: Statin therapy may reduce percent atheroma volume of coronary artery disease. However, the effect of low-dose statin therapy on tissue characterization of coronary plaque is still unknown. Methods: Intravascular ultrasound-virtual histology (IVUS-VH) examination for tissue characterization of coronary plaque was performed at the proximal and distal segments to the deployed stent, which had residual plaque, during and 8.4짹1.9 months after percutaneous coronary intervention (PCI) in 24 segments of 14 patients (mean 51.6짹8 yrs old, 11 males), who were taking atorvastatin 10 mg/day with conventional medication after PCI. Results: Total cholesterol (from 196짹35mg/dL to 170짹37mg/dL, p=NS), triglyceride (from 211짹147mg/dL to 197짹133mg/dL, p=NS) and low-density lipoprotein cholesterol (from 123짹23mg/dL to 105짹27mg/dL, p=NS) were decreased, and high-density lipoprotein cholesterol (from 40.7짹9.0mg/dL to 46.5짹10.7mg/dL, p=NS) was increased during follow up period. Fibrous volume was significantly increased from 9.00짹6.94mm³ to 10.70짹9.06mm³ (p=0.043) over the analyzed lesion segment (4.8짹2.9mm), whereas lumen volume, plaque volume, fibrofatty, dense calcified, and necrotic core volume did not show any significant changes during follow up period. At the minimal lumen site, lumen area (from 9.28짹3.88mm² to 8.68짹3.48mm², p=0.045) and necrotic core area (from 0.77짹0.70mm² to 0.58짹0.54mm², p=0.024) were significantly decreased, whereas vessel area, plaque area, fibrous area, fibrofatty area, and dense calcified area did not show any significant changes. There were no significant correlations among the changes of fibrous volume, necrotic core area, and the changes of lipid parameters. Conclusions: Low-dose atorvastatin therapy may reduce the necrotic core area at the minimal lumen site, which is not related with the lipid lowering effects, although it does not have any effect on plaque volume or area in patients with coronary artery disease.