Whether endothelial dysfunction after sirolimus-eluting stent (SES) implantation is persistent has not been fully evaluated. Endothelial function was evaluated in 152 lesions that underwent follow-up coronary angiography after SES implantation. Lesions were classified into 2 groups according to the duration between SES implantation and follow-up: ≤12 months (n = 95) and >12 months (n = 57). Changes in coronary diameter in response to 10(-8) mol/L (-2.4% ± 6.3% vs -4.9% ± 3.8%, P < .01) and 10(-7) mol/L acetylcholine (Ach; -4.6% ± 7.6% vs -10.7% ± 9.1%, P < .001) in segment proximal to SES were significantly attenuated in the >12-month group than in the ≤12-month group. There were less changes in coronary diameter in response to 10(-8) mol/L (-2.3% ± 4.6% vs -6.9% ± 5.0%, P < .001) and 10(-7) mol/L Ach (-6.5% ± 11.4% vs -16.8% ± 10.5%, P < .001) in segment distal to SES in the >12-month group. Endothelial dysfunction may diminish long after SES implantation.