Growth at the anastomotic site after continuous vascular anastomosis in the pediatric patient remains a problem. Primary end-to-end anastomosis of the infrarenal aorta was performed with absorbable Maxon suture or nonabsorbable Prolene suture in 20 piglets. Ten of the Maxon suture group and nine of the Prolene suture group survived; one pig died of infection. The animals were put to death 6 months after the operation. Each abdominal aorta was removed and a roentgenogram was obtained. The aorta was then burst-tested to 300 mm Hg, measured, and examined both grossly and histologically. All anastomoses were patent and no burst failures were observed in either group. However, Prolene sutures protruded into lumen and were partially embedded in the aortic wall in all animals in the Prolene suture group. Thrombus adhered to the intraluminal Prolene suture in six of nine animals. The growth of the anastomotic area was wider in the Maxon suture group (446.4% +/- 131.8% versus 317.6% +/- 121.5%, p less than 0.05). Stenosis was more common in the Prolene suture group (7/9) than in the Maxon suture group (1/10) (p less than 0.01), but the distal segment was widely patent in both groups. Dilatation at the anastomotic site was present in eight of 10 pigs in the Maxon suture group and in two of nine in the Prolene suture group. Histologic study showed that the area of tissue reaction was more prominent in the Prolene suture group. No sutures were observed in the Maxon suture group. We therefore recommend the use of absorbable Maxon sutures for anastomoses in which the suture line must be able to grow.