Redo coronary artery bypass grafting (CABG) is more challenging than primary CABG in many aspects. Patients who undergo redo CABG are older, more comorbid, and with more sclerotic coronary and noncardiac arteries than seen in primary CABG. Operative procedures are more complicated, reentry of the sternum is sometimes problematic, and dissection of the heart is needed. If patent vein grafts are diseased, they can be sources of thromboembolism, and the patent left internal thoracic artery (ITA) anastomosed to the left anterior descending artery (LAD) must not be injured. The number of redo CABG procedures has been decreasing, because of frequent use of ITA to the LAD in primary CABG, aggressive percutaneous coronary intervention (PCI) by interventional cardiologists, and optimal medical therapy after primary CABG. In-hospital mortality in redo CABG is two to five times higher than that of primary CABG, although outcomes have been improving in recent years despite the patients' more comorbid background. Long-term survival after redo CABG is comparable to that of PCI. The indication for redo CABG should be limited to patients who have jeopardized LAD territory, which is viable. CABG is also preferable to PCI in patients with more diseased vein grafts and low cardiac function. Various technical refinements have also improved the surgical results of redo CABG. Retrograde cardioplegia greatly contributed to proper myocardial protection, especially when the occluded coronary arteries are supplied by patent in situ arterial grafts. The off-pump technique has been used in redo CABG and may be beneficial in a selected, more comorbid population.