This study designed to detect pathological effects of exposure to 2.45 MHz radiofrequency electromagnetic field with low power densities on mature male albino rats. 36 rats at 3-4 months age were used in the study, randomly devided to 6 groups with 6 animals for each group. The groups from 1-5 were exposed to 2.45 MHz radiofrequency electromagnetic field with different power densities : ( 5 MW/cm2 , 1 MW/cm2 , 500 µW/cm2 , 50 µW/cm2 and 10 µW/cm2, respectively). The 6th group represented non exposed control group. The exposed groups received 6 hours of exposure daily for 21 days as an exposure period. Clinical signs were observed daily and body weight and rectal temperature were monitored weekly. At the end of exposure period 3 animals were killed from each group for gross and histopathological examination , the other 3 animals were left for another 21 days without exposure represented post exposure period to detect the ability of rats to recover from the induced pathological changes if existed. The results showed occurrence of clinical signs at all exposed groups and more severe at group 1 manifested by nervous excitation at 1st hour of exposure followed by depression and stagnation to the end of 6 hours of exposure. There was no significant difference between the groups in body weight averages at the 3 weeks of experiment. A significant decrease in post exposure rectal temperature comparing with pre exposure rectal temperature has been noticed at groups 1 and 2 in 1st week and at group 3 in 2nd week of experiment with no significant differences in other groups. Gross and histopathological examination at the end of exposure period revealed presence of some pathological changes at group 1 manifested by perineuronal edema, mild microglial proliferation and congestion in the brain, in lungs there was acute bronchopneumonia with pulmonary vascular arteriosclerosis, there was also mucinous degeneration in duodenal epithelium with congestion of small intestine, in kidneys there was acute cell swelling of renal tubular epithelium with congestion. These changes less severely occurred at the groups 2 and 3, the exposed groups 4 and 5 similar to control did not show any pathological changes. At the end of post exposure period, pathological changes were detected at the groups 1,2 and 3 represented by bronchopneumonia and mucinous degeneration of small intestine .These changes were lighter than those observed at the end of exposure period .