Abstract: AIM　To study the improving effect of NGF (nerve growth factor) on aging-related memory impairment and its possible mechanism of action. METHODS　After direct intrahippocampal injection of NGF, the spontaneous behavior and the memory retention of aging mice were observed using open field and one-trial passive avoidance test. At the same time, the free ［Ca²⁺］ and protein synthesis in hippocampal synaptosomes were measured in vitro by using fluorescence indicator Fura-2/AM and ³H-Leu respectively. RESULTS Compared with the control, NGF was shown to increase significantly the spontaneous behavior and explorative response in the open field, and improve remarkably the memory consolidation of old mice (P<0.05). NGF decreased notably the intrasynaptosomal free ［Ca²⁺］ in hippocampus. Meanwhile, the incorporation of ³H-Leu into the synaptosomal proteins of hippocampus increased significantly. CONCLUSION　NGF showed an improvement effect against the aging-related memory impairment. A decrease of intrasynaptosomal free ［Ca²⁺］ and an increase in protein synthesis may be involved in this effect.