Abstract: ObjectiveTo study the influence of microwave radiation on the structure and function of blood-brain barrier(BBB)in rats.MethodsWistar rats were exposed to microw av es with average power densities of 10,30 and 100mW/cm² respectively.Hematoxylin eosin(HE)staining was used to observe the changes of morphology in BBB.Evans blue(EB)dye and lanthanum nitrate were used to test the permeability of BBB.ResultsAfter being exposed to 10~100mW/cm² microwave,parts of gliocyte showed py knosis and anachromasis in cerebral cortex and hippocampus.The perivascular space widened.In sham-group,the red fluorescence of EB was limited in lumens of blood vessels,while it dispersed out of the blood vessels at 3d in 100mW/cm² group.There was an increase of EB contents in hippocampus in 3~14 d after 10~100mW/cm² microwave radiation.The EB contentincr eased progressively in 10 and 30 mW/cm² groups within 7d and recovered at 14d, while itincr eased progressively in 100mW/cm² group within 14d.Lanthanumions were in the blood vessel in sham-group; and they were observed in circumvascular subendothelial layer at 3d and in extracellular space of brain dinterstitial cells at 7d in 100 mW/cm² group.ConclusionMicrowave radiation can damage BBBstructure and function and resultin the increase of permeability of BBB.