Abstract: Objective To observe the efficacy and safety of different doses of recombinant tissue plasminogen activator(rt-PA) intravenous thrombolysis in the treatment of senile acute cerebral infarction(≥80 years old).Methods Seventy-eight patients with acute cerebral infarction were treated with intravenous thrombolysis using rt-PA，and were divided into low-dose group(0.6mg/kg，40 cases) and standard group(0.9mg/kg，38 cases) according to the drug dose.There were 39 cases in the non-thrombolytic group.Clinical efficacy,National Institutes of Health Stroke scale (NIHSS),modified Rankin Scale(mRS),incidence of intracranial hemorrhageand mortality of the three groups were compared.Results There was no significant difference in total effective rate between low-dose group and standard dose group (P>0.05),and were both higher than that in the non-thrombolytic group(P<0.05).There was no significant difference in NIHSS scores between low-dose group and standard dose group on 1d,7d,15d and 30d after treatment (P>0.05),and were significantly lower than those of the non-thrombolytic group (P<0.05).There was no significant difference in mRS scores between low-dose group and standard dose group(P>0.05),and were significantly lower than that of non-thrombolytic group(P<0.05).The intracranial hemorrhage rate in low-dose group was significantly lower than that in standard dose group(P<0.05).The intracranial hemorrhage rates in low-dose group and standard dose group were higher than that in non-thrombolytic group(P<0.05).There was no significant difference in the mortality between low-dose group and standard dose group(P>0.05)，and were significantly lower than that in non-thrombolytic group(P<0.05).Conclusion Venous thrombolysis is safe and effective in the treatment of senile acute cerebral infarction.Small dose of rt-PA can reduce the risk of bleeding and reduce the neurological deficit.

Key words: Senile acute cerebral infarction, Recombinant tissue plasminogen activator, Intravenous thrombolysis