MANY reports are available describing the experimental replacement of the superior vena cava by various synthetic grafts.1-4Success rates vary, but as yet no really reliable material has been found. Thrombosis of grafts, both immediate and late, has been the main source of failure; and therefore, the frequency of this complication is the standard by which a new technique or material is judged. Autologous vein grafts have been the most successful superior caval grafts.5Thrombus-resistant grafts of Dacron treated with graphite-benzalkonium-heparin (GBH), according to the technique of Gott, have been used with some success.6Untreated Dacron grafts have been associated with high rates of thrombosis.7Inverted jejunal grafts have been reported to have a 100% success rate.8 The experiments reported here constitute a comparative investigation of five different types of graft used for superior vena caval replacement. Long-term follow-up results are reported in all groups.