Objectives: This study aimed at evaluating the long-term changes after bare metal stent implantation in a larger number of patients. Background: Intravascular ultrasound (IVUS) data to evaluate the long-term changes of stented and reference segment beyond 6 months after bare metal stenting are rare. Methods: Using IVUS, we evaluated the serial changes of stented and reference segment between 6 and 24 months after stent implantation in 110 patients with 120 lesions. Serial IVUS images were acquired at 5 equidistant intra-stent sites and at 2 different reference segment sites. The measurements of external elastic membrane (EEM), stent, lumen and intimal hyperplasia (IH=stent-lumen) area were done. Results: In stented segment of overall lesions, mean IH area decreased from 2.6짹1.0 to 2.3짹0.9mm² (p<0.001) and mean lumen area increased from 6.2짹2.0 to 6.5짹1.9mm² (p<0.001) between 6 and 24 months. There was a decrease of mean IH area in 91 lesions (76%) and an increase of that in 29 lesions (24%) between 6 and 24 months. There were no significant changes of EEM and lumen area in the reference segments. Late angiographic restenosis (diameter stenosis > 50%) between 6 and 24 months occurred in 3 lesions. Late target lesion revascularization was performed in 1 lesion. Conclusions: In stented segment, IH regression occurred in most lesions between 6 and 24 months after stenting, resulting in late lumen increase. However, the in-stent IH progression was also observed in 24% of the lesions. No significant changes of EEM and lumen area occurred in the reference segments.