Internal Mammary Artery (1MA) : This is an excellent graft. When left internal mammary artery (LIMA) is anastomosed to LAD, which has more than 70 per cent block, patency at the end of two years is 99 per cent. It falls to 92 per cent at the end of ten years. The right internal mammary artery (RIMA) can be used in situ to bypass RCA, PDA or LAD. It can also be used as a free graft with proximal end anastomosed Lo aorta or left internal mammary artery (LIMA) as a T or Y graft. Long-term patency of free IMA is slightly lower than in situ IMA. In another large series IMA patency was 90 per cent at ten years. After ten years there was no further fall when followed up to twenty years. Internal mammary artery is particularly resistant to athero sclerosis.