A tube graft 2.5 or 5 cm long, was constructed from the peritoneum of the anterior abdominal wall of 12 pigs. It was anastomosed end-to-end as an interposition graft in the infrarenal vena cava. The observation period was 4 months. Three of the six short grafts were venographically patent at 2 weeks, while all the long grafts were occluded. After 4 months two short grafts had recanalized, giving a patency rate of five out of six short grafts. No long grafts recanalized. In three of the patent specimens no clear tissue changes were found with light microscopy, while in the others changes of inflammation and fibrosis were noted. Scanning electron microscopy revealed good 'endothelialization' in two specimens, and partial 'endothelialization' in the others. No dilatation or severe stenosis of the patent grafts was seen. The occluded grafts remained only as a fibrous strand with sutures.