White rats were in vivo exposed to microwave (MW) radiation in the cellular phone communication frequency range to investigate whether such exposure produces functional or morphological damage in the brain. Three groups were investigated: Mobile phone (MP) handset group, mobile stations tower (MT) group, and microwave source (MS) group. Subgroups of all exposed rats were taken for recovery studies. ECoG activities and histopathological changes were recorded before, during and after microwave exposure. As compared to control animals, ECoG patterns in exposed animals were found to be distinctly altered in each case of exposure. Some fluctuations had been recorded in shape, frequency, and amplitude of ECoG pattern accompanied with structural changes in some brain tissue elements.