Background The successful deployment of stents is usually evaluated by angiography alone in the real world. However, there are possibilities of incomplete stent apposition(ISA) after stenting based on visual estimation alone. We performed this study to evaluate the incidence and predictors of ISA after angiographically determined successful drug-eluting stent(DES) implantation. Methods and Results A total of 339 lesions in 299 patients deployed with either paclitaxel-eluting stent(PES,237 lesions in 199 patients) or sirolimus-eluting stent(SES,102 lesions in 100 patients) were consecutively enrolled. Successful stent implantation was defined as less than 20% residual stenosis by visual estimation without major dissection. Adjunctive balloon inflation after stent implantation was performed at operators��� discretion and done in 265 lesions(78.2%). In all lesions, IVUS was performed immediately after angiographically successful stent implantation. ISA was defined as separation of at least 1 stent strut from vessel wall with evidence of blood speckle behind the strut without overlapping a side branch. The overall incidence of ISA was 13.9%(47/339). The incidence of ISA was significantly higher in lesions deployed with SES than PES(23.5% vs 9.7%,P=0.002). Seventy-five percent(35/47) of ISA occurred despite adjunctive balloon inflation. There were no significant differences in the incidence of ISA depending on lesion characteristics such as length, calcification, angulation, eccentricity, contour, bifurcation, total occlusion, or adjunctive ballooning. By multivariate analysis, SES(OR:3.61,95% CI:1.80-7.22), the presence of intracoronary thrombus(OR:4.14,95% CI:1.12-15.29), and non-ST elevation myocardial infarction(NSTEMI)(OR:8.02,95% CI:1.09-59.10) were significant predictors for ISA after angiographically successful stent implantation. Conclusions The incidence of ISA after angiographically determined successful implantation of DES was not infrequent, even after adjunctive balloon inflation. In addition, SES, the presence of intracoronary thrombus, and DES implantation in patients with NSTEMI were independent predictors of ISA after angiographically determined successful DES implantation.