The purpose of this study has been to investigate the effect of dilation on the some mechanical properties of several types of warp-knitted vascular grafts. The structures of warp knit vascular grafts used in the experiments were reverse locknit, locknit, and Tricot. Various mechanical properties of these grafts were determined using devices developed for the purpose. Clinical data obtained were compared with experimental results of warp knit vascular grafts. The most important mechanical properties are found to be creep extension, bursting strengths, and compliance. Preliminary results indicate that vascular grafts are non-compliant and exhibit creep which is predictive of the long term dilation that has been noted in the clinical results. It is found that there is a positive correlation between experimental data and clinical results for at least the grafts tested.