Aneurysmal degeneration, or complete disruption of Dacron grafts (as opposed to anastomotic complications such as pseudoaneurysms), are not expected by vascular surgeons. We have noted two such cases. A 65-year-old male who had an aortobifemoral, double-velour Dacron graft in 1980, presented in 1995 with a large, pulsatile mass in the right lower quadrant, caused by disruption of the mid-portion of the right limb of the Dacron graft. In a second case, a 68-year-old man had a Dacron aortobifemoral graft placed in 1968 which developed diffuse aneurysmal defects, noted clinically in 1987. Both patients had successful graft replacement. A review of the literature indicates that this complication, although unusual, has been noted periodically. Between 1970 and 1996, we identified 11 case reports of aortic Dacron graft rupture, including knitted Dacron (4), double velour (3), woven (1), knitted thin wall (1), and unspecified Dacron grafts (2). An inquiry to the FDA disclosed another 68 cases of Dacron graft failure in addition to those reported in the surgical literature. We present these cases to alert vascular surgeons of the possibility of Dacron graft degeneration, as late as 19 years after implantation. Diagnosis of the complication is readily apparent by clinical examination and imaging studies, which display an aneurysm of the graft remote from the anastomoses.