The left internal mammary artery (IMA) is the preferred native graft for left anterior descending revascularisation owing to its favourable long-term patency and resistance to atherosclerosis. Incomplete ligation of the IMA side branches may cause recurrent angina due to flow diversion. Reoperation for ligating this unligated side branches may be performed but damage to the internal mammary artery or saphenous graft are the potential complications of this procedure. Therefore less invasive endovascular methods should be preferred. In this paper we report a patient with recurrent angina due to a large unligated left internal mammary artery side branch that was succesfully treated with percutaneous coil embolisation.