Abstract: Objective To investig ate the changes and significance of the expression of CaMK Ⅱ in pr imary cultured hippocampus neurons after high power microwave(HPM)radiation.Methods HPM device was used to radiate primary cultured hippocampus neurons,which were observed 1 h after the radiation.The changes of the expression of p-CaMK Ⅱ in primary cultured hippocampus neurons were analysed by immunohistochemistry and other methods.Results The morphological changes of the neurons were observed within 1 h after 30 mW/cm² radiation.Some neurons were atrophied,the cytoplasm was decreased,the dendrites were shorter and thinner.The levels of p-CaMK Ⅱ in the neur ons were weak at 1 h after 0 mW/cm² radiation and strong at 1 h after the radiation by immunohistochemistry.The levels p-CaMK Ⅱ were increased 1 h after radiation.The levels of p-CaMK Ⅱ in primary culturd hippocampus neurons were also increased 1 h after radiat ion by immunofluorescence and laser scanning confocal microscopy.Conclusion HPM radiation may increase the phosphorylation of CaMK Ⅱ in primary cultured hippocamous neurons,which is contributed to the pathophysiological process of the injuries of hippocampus tissue.