The treatment of hemodialysis requires a long-lasting, working vascular access. Particularly at loop-grafts, an inadvertent reversal of hemodialysis lines with consecutive recirculation can occur. Grafts, as opposed to native CIMINO fistulae, are more often threatened by complications or even dead loss. Surveillance programs can extend the life time of these vessel entrances that are becoming a more frequently used option, and can also contribute largely to a general reduction of cost. A previously unpublished, simple clinical procedure to determine the function and direction of blood flow of arteriovenous-grafts was tested. Through compression of the graft with a finger, characteristic stenosis noises are induced that will then be transmitted by the blood flow. Analysis of these noises alone can make the direction of blood flow recognizable in almost 90% of the cases. If these noises are not traceable, we are dealing with fistulae that are endangered by thrombosis and do thus require secondary diagnostic measures. Regular clinical examinations, consisting of inspection, palpation and auscultation as it is described here, can be recommended for the surveillance of grafts.