Objectives: A novel stent design for treatment of true bifurcation lesions was invented and tested. Background: There has been a lot of debate and no definite guideline for adequate treatment strategies for true bifurcation lesions Methods: A side branch stent (called as H-side branch stent) composed of 3 parts: proximal, connecting and distal parts. The distal part for side branch vessel has slope-side stent margin for circumferential coverage of ostium and one radio-opaque marker for targeting to carina. The take-off angle of side branch is same to that of slope-side margin by indentation in the distal part of this stent. The proximal part with 2 radio-opaque markers which will be deployed into proximal segment of main vessel has the significant roles for safe stent delivery and useful guidance for more precise placement of distal part on the side branch ostium. Results of in-vitro test in the bifurcation phantom model made by acrylic resin were evaluated with micro-computer tomography. Animal experiments with this new stent platform were also performed in 3 pigs. Results: In-vitro test and micro-computer tomography showed complete coverage of side branch ostium circumferentially with stent struts without any presence of stent struts in main vessel above the level of side branch ostium. This side branch stents were successfully deployed in all 3 pigs. The results of animal experiments were also similar to those of in-vitro test. Conclusions: In-vivo and vitro tests demonstrated effective modality of this side branch stent for treatment of true coronary bifurcation lesions.