Blood flow through arteriovenous fistulae in patients undergoing hemodialysis needs to be within a certain range for optimal management. Magnetic resonance (MR) velocity mapping is a new modality that allows the noninvasive measurement of blood flow volume. This technique was applied in 13 patients with either a Brescia-Cimino shunt (N = 6) or a Polytetrafluoroethylene graft (Goretex, N = 7). Fistula flow volume measured by MR velocity mapping was 1386 +/- 411 ml/min (mean +/- SD, range 644 to 1921 ml/min). Interstudy reproducibility of MR velocity mapping was good (r = 0.94). Interstudy reproducibility of MR velocity mapping was good (r = 0.94). MR velocity mapping derived flow volumes showed good correlation with values obtained with an indicator dilution technique using Indocyanine Green (ICG) which was performed simultaneously in eight patients (r = 0.86). We conclude that MR velocity mapping is an accurate noninvasive method to quantify flow volume through arteriovenous fistulae in patients requiring hemodialysis.