The purpose of this study was to compare magnetic resonance angiography with duplex ultrasound for defining anatomical features relevant to performing lower limb revascularisation. From June 2003 to June 2004, 30 consecutive patients with chronic lower limb ischaemia underwent magnetic resonance angiography and duplex ultrasound investigations before undergoing lower limb revascularisation procedures. The mean age was 72 years (range: 45-93). Indications for the procedure included resting pain (6 cases), ischaemic ulcer (8 cases), and gangrene (16 cases). We compared magnetic resonance angiography and duplex ultrasonography findings and the differences in the aorto-iliac, femoro-popliteal and infrapoliteal segments were noted. Magnetic resonance angiography and duplex ultrasound findings agreed in 13/15 cases (86%) in the aorto-iliac segment, in 14/17 (82%) in the femoro-popliteal segment, and in 8/11 (74%) in the infrapopliteal segment. In all, duplex ultrasound agreed with intraoperative findings in 97% of cases while magnetic resonance angiography agreed in 81%. These data show that magnetic resonance angiography is less accurate than duplex ultrasound in the infrapopliteal segment. Adeguate training is necessary before duplex ultrasound can be used as the only preoperative imaging procedure.