BACKGROUND Hemodialysis arteriovenous graft (AVG) patency is dependent on favorable flow characteristics. We examined hemodynamic, humoral risk factors, and the effects of stringent flow surveillance coupled with prompt corrective intervention on long-term graft patency. METHODS Over a 29-month period 92 chronic hemodialysis patients with AVG were evaluated monthly by flow surveillance. Clinical diagnosis of failing graft, which promoted angiography and corrective intervention was based on flow reduction, and patient's unique medical history and hemodynamic parameters. RESULTS Graft arteriography revealed stenotic lesions in 94.5% of the cases, necessitating endovascular or surgical angioplasty. Low ejection fraction, early postoperative intervention, and low baseline flow were associated with a statistically significant reduction in intervention-free interval (p < 0.05). Mean AVG flow threshold prior to intervention was 463 +/- 154 ml/min, corresponding to a mean flow reduction of 45 +/- 12%. Total graft thrombosis rate was 0.21 thrombotic episodes/patient year. Primary graft patency at 6, 12, and 24 months was 76, 44 and 35%, and secondary patency 99, 97, 88%, respectively. CONCLUSIONS Stringent flow surveillance policy coupled with prompt intervention has been proven effective in maintaining AVG long-term patency. Patients with decreased ejection fraction, early post-operative intervention, and low baseline AVG flow are prone to graft thrombosis.