Background: Atherosclerosis progression is thought to be one of the mechanisms of late stent failure. Atherosclerosis progression is detected as yellow plaque formation on angioscopy. Cypher sirolimus-eluting stent has been reported to accelerate atherosclerosis progression, but the influence of Endeavor zotarolimus-eluting stent (Endeavor-ZES) or Xience everolimus-eluting stent (Xience-EES) on atherosclerosis has not been clarified. Therefore, we examined the serial changes in extent of atherosclerosis after the implantation of Endeavor-ZES or Xience-EES. Methods and Results: Consecutive patients who received implantation of Endeavor-ZES (n=25) or Xience-EES (n=30) at de novo lesion of native coronary artery and who had successful angioscopy immediately after stent implantation (baseline) and at 1-year follow-up were included in the study. Change in the maximum yellow color grade (grade 0–3) of the stented segment from baseline to follow-up was examined and was compared between Endeavor-ZES and Xience-EES. The maximum yellow color grade decreased significantly from baseline to follow-up in Endeavor-ZES (1.6±1.1 vs. 0.4±0.8, P<0.001), but it did not change in Xience-EES (1.7±1.0 vs. 1.4±0.7, P=0.23). Although the maximum yellow color grade was not different between Endeavor-ZES and Xience-EES at baseline (P=0.72), it was significantly lower in Endeavor-ZES than in Xience-EES at follow-up (P<0.001). Conclusions: Atherosclerosis evaluated by yellow color of the plaque was significantly reduced at 1 year after Endeavor-ZES implantation, but was not changed after Xience-EES implantation.  (Circ J 2014; 78: 1428–1436)