Purpose: Discovering complications of arterio-venous fistula (A VF) in long duration hemodialysis patients. Material và Method: From January 2005 to August 2008, at Thanh Nhan hospital, 14 long duration hemodialysis patients, include: 7 men and 7 women, average aged: 51,8 years, average hemodialysis times: 3 years 8 months were suspected to have AVF complications on the clinic were examined vascular color doppler ultrasound by Voluson ProV 730 ultrasound machine. The results: ultrasound were detected 6 kinds of AVF cpmplications: Blood steal syndrome by less oxy to the hands under the AVF: 7/14 (50 percent) patients, in which: 2 patients have typical clinical symdroms with 1 patient have thick fibre surrounded venous wall = 5,6 mm on the leng about 4 cm, 4 patients have not typical clinical symdroms after the operate of the AVF from 1 to 3 months and 1 AVF after used about 1 year for hemodialysis. Calcification in the AVF 3/14 (21.43 percent) patients. Conclusion: Color doppler ultrasound discovered injury images of the AVF accurately, helping clinical doctors have been oriented in order to treat for the patients timely and exactly.