Introduction. - Up to one-third of autologous arteriovenous fistulae (AVF) created for hemodialysis access will require additional interventions to maintain patency or promote maturation. We describe the technical aspects of duplex ultrasound-guided AVF angioplasty as an alternative to traditional contrast fistulogram and angioplasty. Methods. - The procedure can be performed either in the operating room, interventional procedures suite, or in an outpatient office setting. It is done in a sterile fashion under local anesthesia and light intravenous sedation. With the use of a 12-MHz linear probe and color Doppler imaging, the AVF is surveyed in both the longitudinal and transverse planes, with velocity measurements for identification of areas of stenosis and measurement of AVF blood flow to examine for failure of maturation. Specific areas of stenosis are marked with a skin marker. Percutaneous access into the AVF, guidewire advancement, angioplasty balloon inflation, and deflation are all performed under direct ultrasound visualization. Successful angioplasty is achieved when the vessel diameter, flow, and velocity improve to acceptable ranges. Results. - We have found that duplex ultrasound provides accurate diagnosis of AVF stenosis and non-maturation. Ultrasound information assisted us in the selection of angioplasty balloon sizes and the process of balloon inflation-deflation. Available real-time hemodynamic assessment of lesions before and after interventions provided immediate feedback on the efficacy of treatment. Additional information such as vessel wall recoil, residual stenosis, or plaque dissection after angioplasty guided the upsizing of balloons or deployment of intravascular stents. Conclusions. - Duplex ultrasonography offers the potential for a less expensive and more informative treatment of stenotic or non-maturing arteriovenous fistulas in a variety of outpatient settings. One such future potential location includes the Vascular Laboratory. It offers additional benefits of the avoidance of ionizing radiation and nephrotoxic contrast.