Chronic total occlusion is the complete obstruction of the coronary artery, which lasts for at least 3 months. The loss of blood supply, which is partly reduced by collateral circulation, leads to ischemia with symptoms such as angina pectoris as well as an increased incidence of arrhythmias and heart failure. The most important non-invasive diagnostic tests pointing to ischemia are the ECG and echocardiography, while a definitive diagnosis can be made with coronarography. Scintigraphy is important for the assessment of myocardial viability. The treatment can be conservative, surgical or percutaneous. Despite technological advances and new techniques, CTO revascularizations represent only 10–15% of all coronary procedures. Most procedures are made using an anterograde approach and, in difficult cases, using a retrograde approach through septal and epicardial collaterals. The site of the former occlusion is further protected by a drug eluting stent, which reduces the incidence of restenosis to less than 10%. The incidence of complications is comparable to other interventional procedures, the most common being coronary artery perforation. Studies suggest that CTO revascularization improves survival, left ventricular function and reduces the symptoms of angina pectoris. Revascularization also improves the prognosis of possible myocardial infarction.