A hundred patients with RCAV fistulas we compared with 100 patients with expanded PTFE fistulas created during the same time period. The fistulas were analyzed to compare early and late thrombosis, life table patency, infection rate, venous hypertension, and vascular steal. There was a significantly greater incidence of early thrombosis in the RCAV fistula group. Late thrombosis was seen with equal frequency in both groups. Thirty month patency by life table analysis favored the RCAV group to a significant degree, whereas infections, pseudoaneurysms, venous hypertension, and vascular steal were all more common in the expanded PTFE group. The RCAV fistula remains the ideal form of access but it is less frequently available for women and patients with peripheral vascular disease. Utilization of the expanded PTFE loop fistula requires closer observation and maintenance to keep it functional. Improved methods of patient selection for RCAV fistula using ultrasonographic imaging may allow for increased use of this form of access. Improvement in early patency in RCAV fistulas will magnify the superiority of RCAV fistulas in comparison to expanded PTFE fistulas, however, a prolonged period of venous maturation may be necessary to improve early function.