There are no practical criteria for the use of triple antiplatelet therapy after drug-eluting stent (DES) implantation. In our present report, pooled analysis of 3 randomized studies in patients with diabetes mellitus (Drug-Eluting Stenting Followed by Cilostazol treatment reduces LAte Restenosis in patients with diabetes mellitus trial) and long coronary narrowings (Drug-Eluting Stenting Followed by Cilostazol Treatment Reduces Late Restenosis in Patients with Long Coronary Lesions trials I and II) compared triple (aspirin, clopidogrel, and cilostazol; triple group, n = 700) and dual antiplatelet therapies (aspirin and clopidogrel; dual group, n = 699) after DES implantation. Among pooled population (n = 1,399 patients), 1,173 patients with follow-up angiography were divided into 3 stent length categories (≤20, 20 to 40, and >40 mm). There was no statistical significance of in-stent restenosis (ISR) in ≤20- and 20- to 40-mm categories between 2 groups. However, ISR rate was significantly reduced in triple versus dual group in >40-mm stent length category (12.4% vs 22.1%, p = 0.008). In diabetic patients, triple group also showed significant reduction in the ISR rate in >40-mm stent length category (15.4% vs 32.3%, p = 0.003). According to postprocedural minimal lumen diameter, triple group showed a trend toward a lower ISR than that of the dual group in all categories (p = 0.033 for ≤2.5 mm, p = 0.087 for 2.5 to 3.0 mm, and p = 0.119 for >3.0 mm). In conclusion, the triple group had a significantly reduced ISR in patients with >40-mm stent length after DES implantation compared with the dual group. Therefore, this suggestion for use of triple antiplatelet therapy could be easily applied after DES implantation in routine clinical practice.