Background: Intravascular ultrasound (IVUS) may be more likely to identify characteristics of stent fracture compared with angiography. Methods: Eleven patients with stent fracture detected by IVUS were enrolled. Quantitative IVUS analysis was performed using computerized planimetry. Results: Mean duration between the index procedure and follow-up IVUS was 953 짹 546 days. All cases of stent fracture occurred in Cypher stents. Seven stent fractures were located in right coronary artery (63.6%) and 4 in left anterior descending artery (36.4%). Three stent fractures (27.3%) were associated with instent restenosis and 2 stent fractures (18.2%) with target lesion revascularization. IVUS analysis showed that 2 stent factures were complete (18.2%) and 9 were partial (81.8%); 1 (9.1%) was adjacent to stent metal overlap; and 3 (27.3%) occurred in a coronary aneurysm despite the absence of aneurysm at post-procedure. In addition, 5 (45.5%) were adjacent to calcium (arc of calcification: 118 짹 83째). Vessel area and stent area at the site of stent fracture were significantly larger than those of stented segment. Conclusion: IVUS is helpful to identify stent facture and to understand possible mechanism of stent facture such as calcification and aneurysmal change.