Abstract: Objective: To observe the effect of transcranial ultrasound-enhanced thrombolysis by urokinase on acute cerebral infarction in rats. Methods: The animal model of acute cerebral infarction was made by injecting auto-thrombsis into the left middle cerebral artery. Intravenous urokinase and transcranial ultrasound were given at the same time. The functioning of the nervous system was measured by NSS. The infarct volume was measured after TTC staining. Pathological changes were observed by a light microscope and transmission electron microscope. Results: The NSS score of the large dose urokinase group and the ultrasound plus small dose urokinase group at 24 hours after treatment was lower than that before treatment（P＜0.01） and of that of the infarct group（P＜0.01）. The infarct volume of the two groups was lower than that of the infarct group, but there were no differences between the two groups（P＞0.05）. Remission of pathology was seen under both light microscope and transmission electron microscope. Conclusions： Transcranial ultrasound enhanced thrombolysis by urokinase can accelerate the recovery of the nervous system in acute cerebral infarction rats, diminish the infarct volume, decrease the ischemic changes of the neurons, and reduce the dosage of urokinase.

Key words: Brain infarction, Thrombolysis, Ultrasonic therapy, Rats