Numerous experimental studies,in vitro and in animal models, have demonstrated that ultrasound can accelerate clot lysis. This effect is probably related to the cavitation of microbubbles contained in the medium exposed to ultrasound. Clinical studies show that transcranial application of low-intensity, low-frequency ultrasound identical to that routinely used for diagnostic purposes can improve recanalization rates in patients with acute ischemic stroke. These promising findings should be confirmed in larger studies and using MR or CT angiography to assess recanalization independently. The optimal method of ultrasound-assisted thrombolysis has not been determined yet. Experimental data suggest that it may be enhanced by coadministration of microbubbles used as contrast agents.