The study sought to compare long-term optical coherence tomography (OCT)-based in-stent vascular response between the abluminal groove-filled biodegradable polymer sirolimus-eluting stent (SES) and the durable polymer everolimus-eluting stent (EES) in the TARGET I trial. The TARGET I trial was a prospective, multicenter, randomized clinical trial which enrolled 458 patients with single de novo lesions treated by abluminal groove-filled biodegradable polymer SES and EES. A subset of 43 patients underwent angiography and OCT examinations at 3 years. All OCT images were analyzed at 0.4 mm intervals. A similar increase in angiographic late lumen loss was observed in SES and EES (from 0.05 ± 0.05 vs. 0.05 ± 0.05 mm [p = 0.84] at 9 months to 0.25 ± 0.37 vs. 0.26 ± 0.19 mm [p = 0.99] at 3 years, respectively), without significant differences at 3 years in mean neointimal thickness of stent struts (SES: 0.13 ± 0.02 mm vs. EES: 0.13 ± 0.02 mm, p = 0.80); mean percentage of covered struts (SES: 99.2 % vs. EES: 99.3 %, p = 0.53), or malapposed strut rates (SES: 0.08 % vs. EES: 0.06 %, p = 0.15). The OCT-based in-stent vascular response evaluation found similar vascular healing for the two studied devices, indicating that the luminal loss in EES from 9 months to 3 years cannot be imputed on its coated biocompatible polymer.