Background: A retrograde approach was recently proposed to increase the success rate of PCI for CTO, but this approach is still an incompletely described technique. Method: We analyzed 25 cases (23 patients) of retrograde PCI for CTO, which were done electively (14 cases) or after a failed antegrade approach (11 cases) from July 2006 to June 2008. Results: Septal collaterals were more frequently used than epicardial collaterals (76% vs. 24%). The retrograde wire could be successfully passed to the distal CTO site in 19 cases (76%), without statistical differences in the wire passage rate according to the size or the location of the collaterals. Once the retrograde wire successfully reached the distal CTO site, the occlusion was crossed with the wire in all cases (19 cases) by using 4 different kinds of techniques: retrograde wire crossing (47%), kissing wire (21%), CART (21%), and reverse CART (11%). Among them, the balloon could not cross the CTO in 1 case, and successful recanalization was achieved in 18 cases, yielding a 72% retrograde PCI success rate (18/25 cases). Among the failed retrograde approach cases, 4 cases were successfully treated by switching to the antegrade approach (total PCI success rate was 88% (22/25 cases)). There were several cases of complications related to the collateral donor artery (3 donor vessel dissections, 1 donor vessel acute thrombosis, 1 pericardial tamponade caused by epicardial collateral perforation, and 4 septal collateral perforations), without in-hospital MACE. During the clinical follow-up (median 10.3 months), the overall MACE rate was 18% in the successful retrograde PCI group (1 TLR, 1 non-Q MI). Conclusion: The retrograde approach can improve the success rate of CTO-PCI with acceptable mid-term results. However, strict case selection and systemized approach are essential for the success of this procedure due to the technical complexities accompanied by the potential risk of unexpected complications.