Background: The success rate of percutaneous coronary intervention (PCI) in chronic total occlusion (CTO) has been increased recently due to the technical and devices development. However, the effect of this technical improvement has not been evaluated. Therefore, we sought to evaluate the effect of the systematic approach to improve the success rate of PCI in CTO lesions. Methods: From February 2002 to June 2004, total 96 CTO cases (76 male, mean age: 59 years old) were enrolled in the study. During the periods, we divided the patients who treated by conventional our CTO approach method (Group I) and advanced systematic approach using newer devices and technics (Group II). In group I, the procedures were done either femoral or radial, 6 Fr or 7 Fr guiding catheter and over-the-wire system or microcatheter. Biplane cine usage and bilateral injection were done if necessary. In group II, routine systematic approach with femoral, 7 Fr guiding, microcatheter, biplane cine and bilateral puncture with optional usage of See-saw technique. Results: The success rate of CTO was higher in systematic approach than conventional approach (75% vs 88%), but did not reach statistical difference(p=0.74). Data of the 2 groups were listed in the table. Conclusion: Systematic approach in PCI of CTO lesions using new devices and technique seemed to increase success rate. Further study is necessary in a larger study population.