Retrograde approach via collateral channels in coronary angioplasty for chronic total occlusion (CTO) can improve recanalization success rate. Most interventionalists will meet few cases where the retrograde approach will provide unequaled advantages, but many are held back from taking retrograde approach by lack of proper equipment and expertise. In this article, we give detailed description of all techniques to traverse the collateral channels, and to cross the CTO by retrograde approach. We also illustrate the difficulties in collateral channel crossing with different examples providing a basic guide for case selection purposes.