Introduction : Serial IVUS studies have shown that DES reduce restenosis by inhibiting neointimal hyperplasia (NIH). However, it remains unknown the effect of overlapping DESs (potentially doubling the local sirolimus(S) or paclitaxel (P) drug dose) on NIH and whether it would result dose-related side effects. Animal studies showed overlapping DES further delay the arterial healing and promote inflammation. So we assessed the effects of overlapping DES compared with single stent area using IVUS. Method : Consecutive 53 patients were performed PCI with overlapping same or different DES for a diffuse long lesion. Results : In all 53 patients, 55 lesions were treated with overlapping DES. Nine month-angiographic and IVUS were performed in 46 patient (48 overlapping DES). In 48 overlapping DES, 15 were overlapping of S-P stents, 15 were S-S stents and 18 were P-P stents. On follow-up IVUS, in overall patients, NIH was significantly lower in overlapping area compared to proximal or distal single stent area (0.29짹0.56 vs 0.99짹1.28 vs 0.79짹0.99 mm2, p=0.011). However, these difference was not observed in each separate group (S-P group ; p=0.120, S-S group ; p=0.258, P-P group ; p=0.092). Although stent thrombosis was not noted, 1 late stent malapposition was observed at distal single stent area but not overlapping area. All restenosis were noted proximal or distal single stent area (2 at the proximal edge of the proximal stent, and 3 at the distal in-stent). In most cases, maximum area of NIH was noted at single stent area except 1 case (overlapping with P-P stents). Conclusions : In conclusion, compared with single stent area of overlapping DES, overlapping stent area showed not inferior effect on suppression of neointimal hyperplasia and did not increase risk of side effect of DES.