Background Recent studies have suggested that endoscopic vein harvest (EVH) compromises graft patency. To test whether the learning curve for EVH alters conduit integrity owing to increased trauma compared with an open harvest, we analyzed the quality and early patency of conduits procured by technicians with varying EVH experience. Methods During coronary artery bypass grafting, veins were harvested open (n = 10) or by EVH (n = 85) performed by experienced (>900 cases, >30/month) versus novice <100 cases, <3/month) technicians. Harvested conduits were imaged intraoperatively using optical coherence tomography and on day 5 to assess graft patency using computed tomographic angiography. Results Conduits from experienced (n = 55) versus novice (n = 30) harvesters had similar lengths (33 versus 34 cm) and harvest times (32.4 versus 31.8 minutes). Conduit injury was noted in both EVH groups with similar distribution among disruption of the adventitia (62%), intimal tears at branch points (23%), and intimal or medial dissections (15%), but the incidence of these injuries was less with experienced harvesters and rare in veins procured with an open technique. Overall, the rate of graft attrition was similar between the two EVH groups (6.45% versus 4.34% of grafts; p = 0.552). However, vein grafts with at least 4 intimal or medial dissections showed significantly worse patency (67% versus 96% patency; p = 0.05). Conclusions High-resolution imaging confirmed that technicians inexperienced with EVH are more likely to cause intimal and deep vessel injury to the saphenous vein graft, which increases graft failure risk. Endoscopic vein harvest remains the most common technique for conduit harvest, making efforts to better monitor the learning curve an important public health issue.