Abstract: Physiological aging and aging due to oxidative stress decrease alanine-glutamine dipeptide concentrations in plasma and hippocampus. These conditions impact the decreased availability of glutamine in intracellular and glutathione levels in the hippocampus. Decrease in hippocampal glutathione level will be followed by decreased function of hippocampal neuron. One way to improve the function of the hippocampus is to increase the availability of glutamic acid in hippocampal neuronal cells. This study was designed to obtain the concentration profile of alanine-glutamine dipeptide in plasma and hippocampus and the repair function in the aging hippocampus is known from structural repairs to the mitochondria of neurons. The experimental rats were assigned into a completely randomized design with 2 x 2 x 2 factorial arrangement and three replications. The first factor was the age of the experimental rats, consisted of two levels i.e., 12 and 24 months. The second factor was oxidative stress consisted of two levels, i.e., without or with oxidative stress. The third factor was the concentration of alanine-glutamine dipeptide administration consisted of 2 concentrations, i.e., 0 and 7%. Administration of alanine-glutamine dipeptide 7% can improve function in the aging hippocampus, both in physiological aging or aging due to oxidative stress in younger or aged rats, in normal or oxidative stress rats. This research concluded that the alanine-glutamine dipeptide 7% gave the best results in increased alanine-glutamine dipeptide plasma and hippocampus, glutathione levels, the repair response of mitochondrial structure that mediates the repair function in the aging hippocampus.