Due to serious concerns on very late stent thrombosis (VLST), extended use of dual antiplatelet therapy (DAPT) beyond 1 year after DES implantation has become a common clinical practice despite apparent lack of evidence suggesting its efficacy in reducing VLST. The study population consisted of 12812 patients in the j-Cypher registry who were treated with at least one sirolimus-eluting stent (SES). We assessed the relation between duration of thienopyridine therapy and clinical outcomes with a landmark analysis at 1 year after SES implantation. Among 11713 patients without myocardial infarction (MI), stent thrombosis and stroke at 1 year who were eligible for the landmark analysis, 7414 patients (63 %) were maintained on thienopyridine at 1-year landmark point, while 4299 patients (37 %) had discontinued thienopyridine before 1-year landmark point. Patients in the on-thienopyridine group had more complex characteristics than patients in the off-thienopyridine group. Cumulative incidence of and the risk for definite VLST in the on-thienopyridine group relative to the off-thienopyridine group favored prolonged DAPT, but were not significant [0.9 and 1.2 %, P = 0.1, and adjusted HR (95 % CI): 0.71 (0.47-1.06), P = 0.11]. Cumulative incidence of and the risk for a composite of death, MI, or stroke in the on-thienopyridine group relative to the off-thienopyridine group were also not significant [15.3 and 14.3 %, P = 0.15, and adjusted HR (95 % CI): 0.99 (0.89-1.11), P = 0.89]. Prolonged use of thienopyridine beyond 1 year after SES implantation was not associated with significant decrease in the risks for VLST or for serious cardiovascular events including death, MI or stroke.