The present study deals with the effects of chronic exposure of low-level microwave radiation on developing rat brain. Starting at 35 days of age, male rats were exposed to 2 h/day for another 35 days to a 16.5-GHz microwave radiation field. After the exposure period, the rats were sacrificed, and brain tissues dissected out and used for biochemical assay. Results showed that exposure to a 16.5-GHz radiation caused significant changes in the activity of protein kinase C as compared to the control group. Furthermore, electron microscopic study revealed an increase in glial cell population. These results confirm that brain cell membrane is an interactive site for electromagnetic field causing an inflammation and possibly tumor promotion.