In recent literature, surgically created hemodialysis (HD) arteriovenous fistulas (AVF) have high rates of primary failure. Endovascular treatment holds promise to salvage these fistulae. The outcomes of 119 patients who had a "failing to mature" AVF and presented for endovascular management were evaluated prospectively. All patients underwent a fistulogram. Stenotic lesions underwent balloon angioplasty, and accessory veins underwent obliteration. Technical success was determined immediately after the procedure. AVF salvage was determined by successful use during HD. Patients were followed up for 1 yr, during which primary and secondary AVF patency rates were measured. The distribution of stenoses was as follows: Artery, 6 (5.1%); arterial anastomosis, 56 (47.1%); juxta-arterial anastomosis, 76 (63.9%); peripheral vein, 70 (58.8%); and central vein, 10 (8.4%). Significant accessory veins were present in 35 (29.4%). Mixed lesions were found in 85 (71.4%). The technique was successful in 107 (89.9%), and the AVF was salvaged in 99 (83.2%). Follow-up of salvaged fistulae showed a total event rate of 0.38/access-year, thrombosis rate of 0.12/access-year, and loss rate of 0.04/access-year. Endovascular treatment of "failing to mature AVF" is safe and effective when performed in a dedicated center.