Background: Incomplete stent apposition(ISA) have been suggested to be associated with subsequent stent thrombosis. However there���s no report on results of incompletely apposed stent strut at left main coronary artery(LMCA) protruded from left anterior descending coronary artery(LAD) stent, especially in era of drug eluting stent(DES) which may be more thrombogenic and hard to be reendothelialized. Methods: Patients had been stented to LAD ostium which was protruded to the LMCA with either sirolimus-eluting(SES) or Paclitaxel-eluting stent(PES). Intravascular ultrasound(IVUS) was done after stenting. We divided these patients into two groups, one with complete apposition(CA) group and the other, incomplete apposition(IA) to LMCA because of vessel size discrepancy between LMCA and LAD ostium. We compared 6-month clinical and IVUS follow-up results between two groups. Results: Sixty-two patients were enrolled, 31 CA and 31 IA group. CA group has been implanted SES in 28, PES in 3 patients. SES in 27 and PES in 4 patients were stented in IA group. The length of stent strut protruded to LMCA was 2.7짹2.2mm in CA and 2.2짹1.3mm in IA group with no difference(p=0.237). In follow-up IVUS study, there is no thrombus and no neointima at LMCA stent strut protruded from LAD stent in both CA and IA group. There were no major adverse cardiac events in both groups in 6-month follow-up. Conclusion: The incompletely apposed drug-eluting stent strut protruded to the LMCA from LAD is safe in 6-month clinical and in IVUS follow-up. This results may imply that there might be no need to adjunctive ballooning to incompletely apposed stent strut protruded to LMCA from proximal LAD.