Background With the advent of drug-eluting stents(DES)and much lower rates of target vessel revascularization (TVR),whether adjunctive balloon postdilatation can further optimize outcome is still unknown.The present study was to compare the outcomes of postdilatation with un-postdilatation following deployment of DES.Methods From April 2004 to September 2006,6479 consecutive Chinese patients who underwent DES implantation,including 1769 with postdilatation(1454 male,(57.9 ±10.8)years old)and 4710 without postdilatation(3819 male,(57.9±10.6)years old)were analyzed.Clinical and angiographic follow-up was performed at 7 months.Results Compared with the un-postdilatation group,the postdilatation group had more complex lesions and larger relevant vessel diameter(RVD).In the postdilatation group,in-stent residual restenosis was significantly improved right after the procedure((16.80±5.88)%vs(19.60±6.07)%;P=0.000).There was no statistical difference in the major adverse cardiac events(MACE)rate between the groups(2.9%vs 3.3%;P=0.420),and there were also no statistical differences in death,acute myocardial infarction(AMI)and target lesion revascularization(TLR)rates in the two groups(0.1%vs 0.4%,P=0.127;1.7%vs 1.3%,P=0.229;and 1.5%vs 2.0%,P=0.206,respectively).The in-stent thrombosis rate was almost the same in both groups(0.5%vs 0.5%;P=1.000).Seven months angiographic follow-up results showed that both in-stent and in-segment restenosis rates were lower in the postdilatation group(8.8%vs 15.6%,P=0.000;and 10.5%vs 17.3%,P=0.000),and so were in-stent and in-segment late loss((0.32±0.12)mm vs(0.491±0.13)mm,P=0.000;and (0.24±0.08)mm vs(0.36±0.09)mm,P=0.001).Conclusion Postdilatation after DES deployment was safe and could reduce the restenosis rate,especially for more complex lesions.