['The aim of this study was to explore the determinants of neointimal coverage after sirolimus-eluting stent (SES).', 'Although SES has significantly reduced in-stent restenosis by inhibiting neointimal hyperplasia, insufficient neointimal coverage after stenting might result in adverse outcomes.', 'We evaluated 28 SES lesions with both angioscopy and intravascular ultrasound (IVUS). Quantitative assessments of the lesions and stent expansion were performed by IVUS at the time of stent implantation, and degree of neointimal coverage was judged by angioscopy at follow-up (11 +/- 6 months) whether the stent struts were embedded by the neointima ("complete/incomplete" neointimal coverage).', '"Complete" coverage was identified in 10 (36%), and "incomplete" coverage was identified in 18 (64%). Time from the stenting to angioscopy as well as the lesion and procedural characteristics were similar between the complete and incomplete coverage groups. The IVUS parameters were also similar, except for the final minimum stent cross-sectional area (CSA) (7.0 +/- 1.8 mm(2) in complete vs. 5.3 +/- 1.9 mm(2) in incomplete, p = 0.02) and lumen CSA at the distal reference site (6.1 +/- 1.4 mm(2) in complete vs. 4.9 +/- 1.2 mm(2) in incomplete, p = 0.02). The ratio of the stent area to the vessel area was significantly larger in the complete coverage than in the incomplete coverage group (0.52 +/- 0.11 vs. 0.39 +/- 0.09, p = 0.002).'] Does optimal stent-sizing with intravascular ultrasound contribute to complete neointimal coverage after sirolimus-eluting stent implantation assessed by angioscopy?