Maintenance of vascular access function is vital to the delivery of adequate hemodialysis therapy. Failure of function is associated with significant morbidity and cost. Thus, access surveillance programs are suggested. The most common cause for access dysfunction is stenosis formation within the graft fistula. This may lead to reduced blood flow. The measurement of access blood flow has thus been recommended as the preferred method for surveillance. This article reviews blood flow among other methods for the screening of access dysfunction, the techniques used to measure it, the predictability of access flow measurements in determining the presence of access stenosis and allowing successful; intervention and finally the cost-effectiveness of such surveillance. Review of available evidence would suggest that access flow measurements are the best tests currently available to screen for access dysfunction, and as preventative interventions, such as angioplasty and surgery, are successful, they should be regarded as the present standard of care. This would appear to be a cost-effective strategy. Furthermore, the method of choice for access flow measurement is by ultrasound dilution technology.