Acellular matrix allograft small caliber vascular prostheses. We have developed an acellular matrix vascular prosthesis (AMVP) made by detergent and enzymatic extraction of natural arteries, yielding a tissue framework of collagen and elastin from the original vessel, with preservation of the natural basement membrane at the blood flow surface. These biografts have excellent handling characteristics and suturability, as well as low thromboreactivity. Whole vessel static testing of circumferential compliance (8.9 +/- 1 [SEM] X 10(-2)% mmHg at 100 mmHg) revealed behavior virtually identical to the paired natural vessel from which each AMVP was derived in nine canine carotid arteries. We implanted 16 canine-origin AMVPs into nine dogs (12 femoral and three carotid arteries, and one infrarenal aorta) with no antithrombotic drugs. Angiographic patency was maintained in 15 of 16 (one occlusion within 3 days) for follow-up from 3 days to 6 years, with no aneurysm formation in three AMVP at over 4 1/2 years. Explant analysis revealed preservation of AMVP elastica and collagen with no inflammation or dystropic calcification of the AMVP, and almost total thrombus free flow surfaces. These results suggest that allograft AMVPs could achieve long-term patency equivalent to saphenous veins. 