Aim of the work: is to study the effect of different doses of silibinin on D-galactoseinduced memory impairment in male rats. Methods:60 male rats were divided into four groups, the first three groups were (10 rats each) and the fourth group (30 rats) was subdivided in to three subgroups (10 rats each)I-Control group was injected subcutaneously by physiological saline once daily for six weeks II- D-galactose group was injected subcutaneously by 150 mg/kg of D-galactose once daily for six weeks III-Placebo group 10 ml/kg of 0.5 % carboxymethylcellulose solution was injected intraperitonealy once daily for six weeks IV-Silibinin group include IVa(2 mg/kg),IVb(20mg/kg),IVc(200 mg/kg), silibinin was suspended in 10ml/kg of 0.5 % carboxymethylcellulose solution and injectedintraperitonealy once daily for six weeks. Results: D-galactose group produced significant decrease step-through latency, increase time in the dark and increase in tissue malondialdehyde, nitrite, acetylcholine esterase, tumor necrosis factor-alpha level and caspase activity, it produced significant decrease in tissue catalase activity and brain-derived neurotrophic factor level when compared to control group.There was insignificant change in placebo group and silibinin (2 mg/kg) when compared to D-galactosegroup.While, it produced significant change in silibinin(20 mg/kg) and (200 mg/kg) when compared to placebo group, but it still produced significant change in silibinin (20 mg/kg) and silibinin (2 mg/kg) when compared to control group,it produced insignificant change in silibinin (200 mg/kg) when compared to control group. Conclusion: Silibinin has role in memory disorders which develops efficient therapeutic approaches.