Twenty-three unselected hemodialysis patients with functioning access arteriovenous fistulae were studied prospectively to determine the best technique for detecting stenoses within the fistulae. Combined clinical assessment and fistula assessment monitoring were compared with transbrachial angiography. Fistula assessment monitoring was more accurate (96%) than combined clinical assessment (accuracy, 52%) in stenosis detection. Complications of angiography occurred in 17% of patients; there were no complications of fistula assessment monitoring. Fistula assessment monitoring was better than combined clinical assessment in predicting clinical outcome for arteriovenous fistulae over 6 months and was as good as angiography. Routine fistula assessment monitoring could reduce inappropriate angiography and detect clinically significant silent stenoses. It is an ideal method for monitoring arteriovenous access fistulae.