Aim of the work: is to study the effect of different doses of silibinin on D-galactose induced 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 injected intraperitonealy 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 factoralpha 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-galactose group.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.