Background. Cardiac rehabilitation (CR) is known to have beneficial effects in preventing restenosis and reducing cardiovascular mortality in patients with coronary artery disease. However, it is not known whether CR is cardioprotective in patients with acute myocardial infarction (AMI). The aim of this study was to evaluate the effects of CR on in-stent restenosis following percutanepus coronary intervention (PCI) for AMI patients. Methods A total of 51 AMI patients who underwent PCI and 9 month follow-up angiography in our institution from 2007, November to 2009, April were included. We retrospectively analyzed CR group (CR, n = 22 ) and control group (CON, n = 29). CR was consisted of 6 weeks supervised regular exercise training and 8 weeks of home-based, self-managed exercise. End points were angiographic restenosis rate at 9 months after PCI. Results There were no significant differences in baseline characteristics including age, sex, BMI, smoking status, history of DM and hypertension, family history of coronary disease, level of lipid profile, and use of statin between 2 groups. At 9 months, restenosis, measured as in-segment late luminal loss of the stented coronary area, was smaller in the CR group (0.08짹0.28 mm) compared to the control group (0.43 짹 0.75)(P =0.02). Binary angiographic restenosis, defined as the incidence of percent diameter stenosis of 50% in follow-up angiography, occurred more frequently in control group compared with CR group (14.3% vs 4.5%, respectively, p=0.36). Levels of high-sensitivity C-reactive protein significantly decreased from baseline to 9 months after cardiac rehabilitation(1.5짹2.4 mg/dL vs 0.1짹1.6mg/dL, p=0.05). However, follow-up hsCRP in the control group were not available. Conclusion In patients with AMI, regular physical exercise is associated with a significant reduction in late luminal loss in the stented coronary segment. This effect may be associated with attenuated vascular inflammation, but the further randomized trial is needed to define this results.