Aging induced cognitive impairment has been well documented for many years and several antioxidant strategies have been developed against this impairment. Curcumin is the active component of curcuma longa and has shown antioxidant, antiinflamatory and neuroprotective properties. We hypothesized that curcumin would have an influence on cognitive functions in aged female rats. The purpose of the present study was to investigate the effects of curcumin supplementation on cognitive impairment evaluated by Morris water maze (MWM) as well as the oxidative stress induced by aging in female rats. Rats were randomly divided into either control or curcumin-supplemented groups. Curcumin or vehicle (corn oil) were given once daily for a period of 12 days, beginning 7 days prior to and 5 days during the behavioral tests. Behavioral assessment was performed in MWM. At the end of the behavioral test, blood samples and brain tissues were taken for the analysis of malondialdeyde (MDA), protein carbonyl and glutathione levels. During the training session, curcumin supplementation decreased latency to reach to the platform and the total distance traveled. During the probe trial, curcumin supplementation increased the number of platform crossings. In addition to the behavioral testing, biochemical results showed that MDA levels decreased in brain tissue by curcumin supplementation. It may be concluded that, curcumin supplementation improves cognitive functions by decreasing the lipid peroxidation in brain tissue of aged female rats.