Objective:To evaluate the protective effect and the long term clinical outcomes of double guide wire at side-branch compared with single guide wire in dealing with true bifurcated lesion. Methods:A total of 138 patients with true bifurcated lesions treated by simple stenting were enrolled and randomly divided into two groups:the single wire group (68 patients,with single wire at side-branch)and the double wire group(70 patients,with double wires at side-branch). The following acute post-stenting complications were evaluated:aggravated stenosis and instant occlusion of side-branch,time of exchanging guide wire and the rate of stenting at the side-branch. At the same time,restenosis and occlusion of main vessel and side-branch were evaluated by coronary angiograph(CAG)within 9-12 months follow-up. Results:The incidence of side-branch instant occlusion and aggravated stenosis,time of exchanging guide wire and the rate of stenting at the side-branch in the single wire group were higher than those in the double wire group (P < 0.05). There were no significant differences in the incidence of main vessel restenosis between the two groups (P > 0.05),however,the rate of side-branch occlusion in the double wire group was lower than that in the single wire group within 9-12 months follow up (P < 0.05). Conclusion:Double wire at side-branch in dealing with true bifurcated lesion significantly reduces the happening of side-branch instant (and long term)loss,prevents the aggravation of side-branch stenosis in which case stent needed and enhances the safety of surgery compared with single wire. Double wire technique may also reduce the adverse cardiac events in patients with true bifurcated lesion.