Introduction: There are only scarce data regarding the cardiovascular impact of arteriovenous fistula after kidney transplantation depending on fistula flow. Methods: We performed a single‐center, prospective, cohort study including 49 patients with a functional fistula at 1 year from kidney transplantation. Patients were convened for a clinical work‐up, a biological analysis, a fistula's Doppler ultrasonography and an echocardiography. Main judgment criterion was comparison of echocardiography parameters between patients with relative (fistula flow >1 L/min and a fistula flow/cardiac output ratio >20%), absolute high‐flow fistula (fistula flow >2 L/min) and normal‐flow fistula. Results: High‐flow fistula frequency was 69%. Significantly higher left ventricular end‐diastolic and systolic diameters were observed in this group compared with the normal‐flow fistula group (53 ± 6 vs. 48 ± 7 mm; p = 0.04 and 33 ± 6 vs. 28 ± 8 mm; p = 0.02) and between the absolute and relative high‐flow fistula subgroups (56 ± 6 vs. 51 ± 6 mm; p = 0.009 and 35 ± 6 vs. 31 ± 5 mm; p = 0.01). The study showed no other significant differences. Conclusions: This study showed a significantly higher but not pathological left ventricular end‐diastolic and systolic diameters values in patients with high‐flow fistula compared with patients with normal‐flow fistula and between patients with respectively absolute and relative high‐flow fistula. [ABSTRACT FROM AUTHOR]