Periodical access flow measurements can predict the development and presence of vascular access flow-limiting stenosis and subsequent thrombosis. Access flow measurement has become a standard in vascular access care. Different techniques to measure access flow are available. The aim of this study was to compare an integrated access flow measurement device, based on thermodilution (Blood Temperature Monitor, BTM, Fresenius Medical Care, Bad Homburg, Germany), with the gold standard, the HD01 (Transonic Systems Inc., Ithaca, NY), whose technique is based on saline dilution. In 40 patients with end-stage renal disease, 40 vascular accesses were studied to determine the correlation between access flow measurements by both techniques. Reproducibility of access flow measurements by both techniques was assessed in 20 patients on a weekly interval.A total of 40 measurement series were performed. Average access flow measured with the saline technique and the thermodilution technique was 1053 (+/-495) ml/min and 1034 (+/-527) ml/min, respectively (p = ns) (n = 40). Correlation between access flow measurements by both techniques expressed in R was 0.79 (r = 0.89). Reproducibility of saline and thermodilution subsequent measurements with a weekly interval, expressed in relative difference (Delta xrel) was 13 (+/-11)% and 24 (+/-14)%, respectively (p < 0.01) (n = 20).BTM access flow measurements correlated well with the HD01 access flow measurements. However, the better reproducibility of HD01 and shorter measurement time compared with BTM access flow measurements should be considered when implementing access flow measurement to prevent vascular access failure.