Samples of Dacron and Teflon tubing that were obtained from unused vascular-graft remnants were irradiated with 1000 to 8000 rad (10 to 80 Gy) and compared in tensile strength and elongation with unirradiated specimens. No significant difference in these parameters was found. These levels of single-dose irradiation may be assumed to be similar to those used in fractionated irradiation of human malignant neoplasms. Therefore, it can be concluded that irradiation at clinical dose ranges does not affect the tensile strength and elongation of vascular graft material. Polyethylene tubing, on the other hand, is strengthened to a minor degree by single dose irradiation with 1000 to 8000 rad (10 to 80 Gy).