The efficacy of regional thrombolysis for treating leg ischaemia is well established, but the duration of infusion and the frequent complications remain major disadvantages. By delivering recombinant human tissue type plasminogen activator (rt-PA) as pulsed intra-thrombus 5-mg aliquots combined with catheter manipulation to maintain an intra-thrombus location, the average time taken to achieve thrombolysis in 20 consecutive patients with infra-aortic occlusions was 109 min. Immediate thrombolysis was achieved in every case. Pulsed delivery of high dose rt-PA significantly accelerates thrombolysis, decreases dose and reduces costs.