Background and Objectives: Previous studies suggested that asymmetric stent expansion after sirolimus-eluting stents (SES) implantation did not affect suppression of neointimal hyperplasia (NIH). However, there were no data regarding paclitaxel-eluting stents (PES) and comparison of stent eccentricity (SE) between SES vs. PES. The aim of this study is to assess the significance of SE using intravascular ultrasound (IVUS) analysis. Subjects and Methods: This study represents an IVUS sub-study of the Post-stent Optimal Expansion (POET) trial, a prospective, multicenter, randomized trial to evaluate the efficacy of the non-compliant adjuvant balloon compared with semi-compliant balloon with SES or PES randomly allocated. Each group was divided into two groups, based on the mean value of SE (determined by minimum stent diameter divided by the maximum stent diameter in the narrowest portion of stent); concentric (��� mean SE) and eccentric (< mean SE) group. We compared SE and its relation with NIH parameters between SES and PES. Results: From the total enrolled patients (n=301), follow-up IVUS was performed in 250 patients. Mean SE of SES (0.896짹0.023) was significantly higher than that of PES (0.888짹0.026, p=0.012). There was no difference in NIH volume parameters between concentric vs. eccentric group of both stents. In addition, there was no difference of restenosis rate in the both groups (table). Conclusion: This study demonstrated SE of SES was significantly higher than that of PES. However, SE of PES, similar results with that of SES, did not affect NIH growth, despite of adjunctive high pressure post-dilation.