PURPOSE: To evaluate the safety and performance of ultrasound-enhanced thrombolysis in the treatment of acute thrombotic or embolic occlusion of the lower limb arteries. METHODS: From April 2005 to July 2006, 25 patients (15 men; mean age 64.1 years, range 37-82) presenting with acute (<14 days old) occlusions of the lower limb arteries were treated with local thrombolysis [recombinant tissue plasminogen activator (rtPA)] in a dosage of 1.0 mg/h using the EKOS Lysus Peripheral Catheter System with an ultrasound core. No bolus injection of rtPA was given. The mean occlusion length was 25.1 cm (range 2-70). RESULTS: The technical success rate was 100%. Total clot removal was achieved in 22 (88%) patients after 16.9 hours (range 5-24) using a mean 17 mg (range 5-25) of rtPA. In 8 cases, total clot removal of the main lesion was achieved after 6 hours (6 mg of rtPA). In 1 patient, lysis was stopped after 2.5 hours because of bleeding due a dislocation of the introducer sheath. In 2 cases, total clot removal could not be achieved; these patients were successfully treated with thromboaspiration. At the 1-month follow-up, the treated vessel was still patent in 20 patients. Two reocclusions occurred; 1 was treated with a bypass graft and the other with conservative therapy. There were no cases of amputation or death during follow-up. There were no side effects related to rtPA or the catheter system. CONCLUSION: This study demonstrates that local lysis of acute arterial occlusions using the Lysus Peripheral Catheter System is safe and effective. Blood flow is restored quickly.