Objectives Excess iron in the brain has been implicated in the pathogenesis of neurodegenerative disorders. The present study was designed to investigate the effect of postnatal iron administration on memory, hippocampal serotonin (5HT) and γ-aminobutyric acid (GABA) levels and oxidative stress markers in adult male rats. Methods Thirty pups at age of 7 days weighting 50-52 grams were randomly divided equally into two groups : control (normal pups) and iron overload group treated with ferrous sulphate (3 mg/kg/day,intraperitoneally) for consecutive 21 days. Spatial and avoidance memories were tested using radial arm maze and passive avoidance tests. Hippocamapl levels of 5HT, GABA, serum total antioxidant capacity (TAC), and total peroxide (TP) were determined. Histopathological studies using H&E and Prussian blue stains were done. Results Iron overloaded rats showed impaired working memory in radial arm maze and impaired avoidance learning in passive avoidance test compared to the controls. Iron overload induced a significant decrease in the hippocampal levels of both 5HT and GABA. Levels of TAC were decreased and total peroxide was increased in iron overload group as compared to control group. Moreover, in contrast to the control group, positive iron depositions in the form of blue particles were detected in different areas of the hippocampus of iron overload group. Conclusion postnatal iron administration resulted in memory impairment possibly through alternation in hippocampal 5HT and GABA levels and oxidative stress