Background: The acute impact in vivo from a self-expanding stent on the vessel wall has not been sufficiently evaluated. Objectives: We sought to compare acute in vivo injury on the vessel wall and clinical impact between a self-expanding coronary stent and conventional balloon-expandable stents immediately after stent implantation. Methods: We included forty patients (45 vessels) with stable or unstable angina who were assigned to either the self-expanding stent (vProtect짰 Luminal Shield) group (n = 9; group 1) or the conventional balloon-expandable stent group (n = 36; group 2). Optical coherence tomography (OCT) was performed after stent deployment as were qualitative and quantitative assessments of tissue prolapse, intra-stent dissection, edge dissection, and incomplete stent apposition. Results: Tissue prolapse was visible in all vessels in both groups. The corrected tissue prolapse area by stent length was larger in group 2 than group 1 (0.06 짹 0.06 vs. 0.02 짹 0.01 mm짼, p <0.001). Intra-stent dissection was more frequently seen in group 2 (33/36 vs. 4/9 vessels, p = 0.004) and the mean length of the dissection flap was greater in group 2 than in group 1 (277.6 짹 110.0 vs. 76.9 짹 103.7 µm, p<0.001). Although edge dissection was not detected in group 1, it was visible in 19/36 vessels (52.8%) in group 2. The frequency of incomplete stent apposition was not significantly different between group 2 and group 1 (23/36 vs. 7/9 vessels, p = 0.7) but the mean depth of incomplete stent apposition was greater in group 2 than in group 1(268.2 짹 72.1 vs. 178.2 짹 156.7 µm, p = 0.03). Conclusions: A self-expanding stent was associated with less intra-stent dissection and edge dissection than conventional balloon-expandable stents with OCT.