Aim To determine optimal duration with dual antiplatelet therapy,optical coherence tomography (OCT) was used to assess neointimal coverage after implantation of sirolimus-eluting stents. Methods Stent strut intimal coverage at 9 months after Helios stent implantation was assessed by OCT at 1-mm intervals in 10 patients who accepted one year of dual antiplatelet therapy. Results Of 2 063 struts in 296 mm examined,64.6% had no intimal coverage. The average intimal thickness was 95.70±66.62 μm while average lumen percentage of neointimal area was 5.061 8%±5.662 5%. Conclusion The percentage of delayed intimal coverage was high at 9 months after Helios stent implantation,which suggested that duration of dual antiplatelet therapy should be prolonged after Helios stent implantation.