A measurement system has been designed and constructed at NIST for the study of the mechanical properties of synthetic and bovine vascular materials. The measurement technique was validated on latex, where good agreement was found with the Neo-Hookean model. Measurements were also made on expanded polytetrafluoroethylene, which is commonly used for vascular grafts. The measurements of this material were carried out over a pressure range greater than would be seen in vivo. However, the strains were still small enough to effectively apply the Neo-Hookean model to these data.