There are limited data showing right ventricular preload increase due to high-flow arteriovenous fistulas (AVFs). This cross-sectional study investigated whether high AVF flow had an impact on right ventricular function in patients undergoing hemodialysis. Sixty-four patients aged between 18 and 85 years who were on routine hemodialysis with >2 hemodialysis sessions per week for at least 3 months via an AVF were studied. Patients with inadequate flow fistulas, severe chronic obstructive pulmonary disease, history of pulmonary embolism, primary pulmonary hypertension, severe mitral, aortic or pulmonary regurgitation, and/or stenosis were excluded. After an initial evaluation, 44 patients (mean age: 58.50 ± 16.84, male:female = 23:21) were considered eligible. Right ventricular function was assessed by tricuspid annular plane systolic excursion (TAPSE). AVF blood flow was measured with duplex ultrasound. There were 15 patients (34.1%) with a TAPSE of <16 mm. AVF blood flow was significantly higher in patients with impaired versus normal right ventricular function (1631.53 ± 738.17 vs. 1060.55 ± 539.92 min/ml, respectively, P = 0.003). Low left ventricular ejection fraction (odds ratio OR: 1.15, 95% confidence intervals CI: 1.007-1.334, P = 0.04), high interventricular septum thickness (OR: 1.64, 95% CI: 1.104-2.464, P = 0.01), and high AVF blood flow (OR: 1.00, 95% CI: 1.000-1.003, P = 0.03) were independent predictors of impaired right ventricular function. In addition to known risk factors that predominantly increase right ventricular afterload, excessive AVF blood flow was found to be independently associated with impaired right ventricular function, possibly by increasing right ventricular preload.