The mobile phones emitting electromagnetic radiation(EMR) may be mainly absorbed by brain tissue since they are often used nearly skull. Melatonin, the chief secretory product of the pineal gland, was recently found to be a potent free radical scavenger and antioxidant. The aim of this study was to examine 900 MHz mobile phone-induced oxidative stress that promotes production of reactive oxygen species(ROS) in neural tissue damage in hippocampus and the role of melatonin against possible oxidative neural tissue damage in hippocampus in rats. Animals were randomly grouped as follows: 1)Cage control group 2)Control group 3)Study groups: i)900 MHz EMR exposed (30 min/day for 10 days) group and ii)900 MHz EMR exposed + melatonin (100 μgkg-1 s.c. before the daily EMR exposure) treated group. Malondialdehyde (MDA, an index of lipid peroxidation), was used as a marker of oxidative stress-induced neural tissue impairment. Superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) activities were studied to evaluate the changes of antioxidant status. In the EMR exposed group, while tissue MDA levels increased, SOD, CAT, and GSH-Px activities were reduced. Melatonin treatment reversed these effects as well. In this study, increase in MDA levels and decrease in SOD, CAT, and GSH-Px activities demonstrated the role of oxidative mechanism induced by 900 MHz mobile phone exposure, and melatonin, via its free radical scavenging and antioxidant properties, ameliorated oxidative tissue injury in rat hippocampus. These results show that melatonin may exhibit a protective effect on mobile phone-induced neural tissue impairment in hippocampus in rats.