Background: We used intravascular ultrasound (IVUS) to evaluate the association of tissue prolapse (TP) with short- and long-term clinical outcomes after stent implantation in 418 acute myocardial infarction (AMI) patients (155 ST segment elevation and 263 non-ST segment elevation MI). Methods: We evaluated the incidences of stent thrombosis, no-reflow, and long-term clinical outcomes. Results: After stenting, TP was detected in 34% without difference according to the stent types. Acute and subacute stent thrombosis occurred more frequently in patients with TP compared with those without TP (3.5% vs. 0.7%, p=0.035, and 4.2% vs. 0.7%, p=0.013, respectively). No-reflow was developed more frequently in patients with TP compared with those without TP (25.4% vs. 9.8%, p<0.001). Creatine kinase-MB and cardiac-specific troponin I were elevated more significantly after stenting in patients with TP compared with those without TP (=+9.0짹25.2 U/l vs. -4.2짹41.6 U/l, p=0.001 and =+10.0짹43.5 ng/ml vs. -1.2짹35.6 ng/ml, p=0.005, respectively). There were no significant differences in the incidences of cardiac death, MI, and target vessel revascularization at 1-year. Multivariate analysis showed that TP was the independent predictor of composite of acute and subacute stent thrombosis [odds ratio (OR)=4.211; 95% CI 1.198-14.805, p=0.025] and composite of acute stent thrombosis and no-reflow (OR=2.551; 95% CI 1.315-4.952, p=0.006). Conclusions: TP was associated with short-term complications (acute and subacute thrombosis and no-reflow phenomenon), however it was not affect long-term clinical outcomes after stent implantation in patients with AMI.