Percutaneous catheter-delivered ultrasound energy for arterial recanalisation was applied in eight patients with peripheral vascular disease. Four patients had severe claudication with total occlusion and four high-grade stenosis in a superficial femoral or popliteal artery. A prototype ultrasound probe, with a frequency of 20 kHz and a power output of 20-35 W/cm2, was ensheathed in a 7F catheter and advanced to the occlusions under angiographic guidance. Three of four complete occlusions were recanalised in 120s or less, leaving a residual stenosis of mean (SD) diameter 54 (5)%. Ultrasound energy reduced the diameter of the isolated stenoses from 77 (14)% to 37 (21)%. All lesions were further treated with balloon angioplasty, resulting in a mean residual stenosis of 20 (9)%. There was no evidence of arterial emboli, dissection, spasm, or perforation. The major limitations of this ultrasound system are ease of steering and flexibility. Percutaneous catheter-delivered ultrasound energy appears promising for safe and effective use in atherosclerotic peripheral vessels to reduce arterial stenoses and recanalise complete arterial obstructions.