Objective To study the protective effect and influence of Naomaitong （Remove obstruction of cerebral vessels） on the time window of thrombolysis for the cerebral ischemic rats with thrombo-embolism. Methods The rats were randomized into sham-operated group

model group

urokinase （UK） thrombolysis group

Naomaitong group

and UK plus Naomaitong group （associated group）. The cerebral ischemic rat models with thrombo-embolism were made by blocking sylvian artery. The rats were administrated local thrombolysis with duct to artery at the time-point of 3

6

and 9h after cerebral ischemia. At 24h of administration through artery

the pathologic changes of brain and the symptoms of nerve system were observed to determine the brain water ratio （BWR） and the change of cerebral infarction area （CIA）. Results Compared with the sham-operated group

in all model groups

the score of nerve system symptoms increased

the BWR and CIA increased

and the brain pathological changes became worse; in all thrombolysis groups

the score of nerve system symptoms decreased

the BWR and CIA decreased

and the brain pathologic changes became relieved; within 6 hours

the improvement of above-mentioned thrombolysis indices was especially remarkable; in the associated group

all indices at the corresponding time-point were improved significantly than those of the thrombolysis group and Naomaitong group. Conclusion Thrombolysis through artery given at different time is protective for the ischemic tissues

but the effect of treatment given at 3 and 6h after ischemia is better than that of 9h. Naomaitong enhances the protection

functioning to prolong the time window of thrombolysis.