Autologous arteriovenous fistula (AVF) has been preferred over arteriovenous graft (AVG) because they were associated with a higher patient survival rate. However, with the recent increase in the frequency of diabetes mellitus and peripheral vascular disease in hemodialysis patients and the increasing proportion of elderly patients, there are many difficulties in creating AVF. Because of such facts, it is true that there is a tendency to prefer AVG, but AVG has the disadvantage that thrombotic occlusion can occur without the preceding stenosis. In AVG, the thrombectomy can be done successfully in a relatively short time. However, since the number of elderly HD patients is increasing recently, complications may occur during endovascular treatment (EVT) or its sedation process although EVT is a relatively simple procedure compared with a surgery. In contrast to AVG, AVF can be rescued more easily by confirming the stenotic lesion before the thrombosis and solving the stenosis. From this point of view, in order to increase the AVF use, during the period of AVF maturation after its creation, angioplasty with a balloon catheter, so called as balloon assisted maturation (BAM) when maturity was not reached, is performed frequently. In general, the treatment for immature AVF is done by increasing the blood flow after resolving stenosis or in a few cases, it targets to sizing the blood vessel up. However, as the recently revised 2019 KDOQI guideline raises the strong questions about the usefulness of pre-emptive correction and does not recommend it anymore, it also does not mention so-called 'Rule of 6' for AVF maturation criteria similarly. And, in the new KDOQI, it is also written that it is inadequate to conclude that the salvage therapy such as BAM for AVF maturation is useful. Therefore, although ultrasound maturation criteria such as 'rule of 6' or university of Alabama (UAB) criterion is really helpful for screening immature or mature AVF, clinical maturation, based on physical examination by skillful HD expert nurse or so-called cannulation readiness, is more important to decide whether AVF can be cannulated or not.