Objective To evaluate the effect of calorie restriction(CR)on learning and memory ability of early old age rats by behavioral study.Methods Male SD rats with the age of 18 months were subjected to restricted intake in CR group(n=18)by 60%comparing with that of rats fed ad libitum(AL)(n=15)for 6 months.Escape latency(EL)and time and distance covered in each quarter were evaluated by Morris Water Maze (MWM).Histochemical stained for SA-β-GAL with frozen section of rat brain.Results EL of CR group was shorter than that of AL group(P=0.038).The percentage of time(AL=30.61±6.10;CR=26.58±5.06)and distance(AL=31.23±7.82;CR=26.27±5.5)showed statistically significant difference in that of quarter Ⅱ(P=0.027and P=0.029).The percentage of SA-β-GAL positive staining was smaller in pyramidal cells of CA3 region of hippocampus of CR rats than in AL rats.Conclusion The 6-month treatment of 60% CR delayed the agerelated inability to learn and improved the accuracy of the memory of early old rats.The behavioral change may contribute to CR delayed senescence of neurons at hippocampal region.