Background: High dose Pioglitazone reduced neointimal proliferation in patients with diabetes mellitus (DM) who underwent percutaneous coronary intervention (PCI) with bare metal stents via the PPAR-r receptor. We evaluated the clinical outcomes, angiographic results and intravascular ultrasound (IVUS) results of patients taking pioglitazone after PCI. Methods: This study was a single center, prospective randomized study. The study population currently included 121 diabetic patients with coronary artery disease, assigned to 51 patients taking 15mg of low dose pioglitazone daily in addition to their diabetic medications and 70 patients without pioglitazone(control group) after index procedure. We estimated all-cause death, myocardial infarction(MI), target lesion revascularization(TLR)ed of the IVUS finding on atheroma plaques and restensosis, angiographic finding. Results: Ninety-seven patients (38 in the pioglitazone group and 59 in the control group) completed follow-up angiography. Among them, follow-up IVUS was done in fifteen patients(18 in the pioglitazone group and 16 in the control group). There were no significant differences between the pioglitazone group and the control group of the baseline clinical demographics and angiographic findings. There was no difference of major cardiac adverse events (MACE), TLR, TVR and The rate of in-stent restenosis(ISR) between two groups. (MACE 11.8% vs. 12.9%, p=0.854, TLR 3.9% vs. , 5.7%, p=NS). There were statistically no difference of neointimal volume index, percent neointimal volume, percent change of plaque volume index between two groups on IVUS study. Conclusion: The results of this study showed that low dose pioglitazone, in diabetic patients who underwent PCI, was not associated with reduced MACE and restenosis. And, low dose pioglitazone didn���t affect atheroma plaques and neointimal proliferation in the stents by IVUS.