Abstract: Objective To evaluate the effects of 2000 μW/cm² electromagnetic radiation on hippocampus ultrastructure and apoptosis-related genes.Methods Totally 100 Wistar rats were randomly divided into normal control,sham-radiated,and 1,2 and 3 hours/per day radiation groups.The rats in the radiation groups were exposed to microwave of 2000 μW/cm² on their heads and then the morphological changes in the hippocampal neurons were detected by transmission electronic microscopy and the expressions of Bcl-2 and Bax protein were detected by immnunohistochemistry and the expression of caspase-3 by western-blot.Results Microscopic observation revealed that the chromatin coacervation and chromatin of hippocampal neurons gathered along the inside of the nuclear membrane in radiation group.The structure of synaptic interface changed.Compared with the normal control group,the expression of Bax and caspase-3 protein increased and Bcl-2 protein decreased in radiation group.Conclusion The electromagnetic radiation exposure of 2 000 μW/cm² can induce the abnormality of neuronal apoptosis in rat hippocampus.The machanism of hippocampus neuron injury involves in the expression of apoptosis related genes,such as Bc1-2,Bax,and caspase-3.