Backgrounds: Data regarding the efficacy of additional ballooning at the site of two or more overlapping drug-eluting stent (DES) implantation in diffuse long lesion angioplasty are limited. This study was aimed to evaluate the efficacy of additional ballooning in terms of clinical and angiographic outcomes up to 6 months. Methods: A total 50 patients (pts, male 37, mean age 59.8 짹 9.9 years) with diffuse long lesion were randomly treated with either Sirolimus-eluting stent (SES; Cypher) or Paclitaxel-eluting stent (PAS, Taxus). The clinical and angiographic outcomes up to 6 months of 32 pts without additional ballooning group (No balloon group) were compared with those of 18 pts with additional ballooning group (balloon group). Results: Baseline clinical and procedural characteristics were similar between two groups. Lesion length (38.8짹18.8 mm vs. 31.1짹16.5 mm in balloon group, p=0.20), lesion type B1/B2 and C (90.7% vs. 100% in balloon group, p=0.82) and DES type were similar between two groups. Binary restenosis at 6 month were similar between two groups (3.1% vs. 0% in balloon group, p=0.45). Major adverse cardiac event (MACE) were similar between two groups (6.2% vs. 5.6% in balloon group, p=0.92, Table). Conclusions: The additional ballooning at the overlapping site of multiple DES implantations in diffuse long coronary lesions showed no significant benefits in terms of angiographic and clinical outcomes compared to those of pts without additional balloon. This might be associated with higher concentration of drugs at the overlapping DES sites which further inhibit intimal proliferation.