Objective To investigate the risk factors and the influence of intravenous thrombolysis of acute cerebral infarction with cerebral microbleeds(CMBs)by SWI.Methods 1 64 patients with acute cerebral infarction were enrolled in this study.All pa-tients were scanned with routine MRI and SWI.According to the presence of CMBs on SWI,the patients were classified into two groups:CMBs group(73 cases)and non-CMBs group(91 cases).Past history was recorded and risk factors of CMBs were explored. 76 cases patients(including 35 cases of CMBs group and 41 cases of non-CMBs group)were treated by intravenous thrombolysis and rescanned with routine MRI and SWI to compare the changes in the number of CMBs and hemorrhage transformation 24 hours after thrombolysis.Results The difference age,hypertension,lacunar infarction and leukoaraiosis between the two groups were significant (P <0.05).The difference of CMBs and hemorrhagic transformation between the two groups treated by thrombolysis were not sig-nificant(P >0.05).Conclusion Acute cerebral infarction with CMBs are influenced by age,hypertension,lacunar infarction and leu-koaraiosis.Thrombolysis in acute cerebral infarction with CMBs can not augment the incidence of hemorrhagic transformation.