Objective To investigate and compare the effects of etomidate or propofol on spatial cognitive,exploring,learning and memory abilities and hippocampus tissue in rapid development period of rats.Methods Thirty-nine SD rats with anage from 17 to 18 days were randomly divided into group C(10 ml/kg of normal saline),group E(5 mg/kg of etomidate),group P(50 mg/kg of propofol)(n=13).They were all single injected intraperitoneally.The tests of cognitive function were performed in Open Field Test(OFT),Hole Board Test and Ymaze Test at 3 hours postanesthesia awake.HE staining method was uesed to observe the morphology of hippocampus neuron tissue and immunohistochemistry(IHC) method was uesed to detect the expression of aspartic acid specificity cysteine protease (caspase-3) in hippocampal neurons.Results In the OFT,there was no significant difference between group C((3.70 ± 1.06)s,(39.10 ± 11.89)s)and group E,P((4.40 ±2.01)s and (4.60 ± 1.96) s,(37.90 ± 11.88) s and (36.30 ± 15.68) s) about the retention time in central check and the locomotion (P ＞ 0.05).In the Hole Board Test,the rats of groups E and P(12.00 ± 3.13,10.00 ± 2.79) about the times of rats stretch into the hole were significant different comparing with group C(16.30 ±4.62) (P＜0.05).In the Ymaze Test,compared with group C,the group E in the right number and total reaction time were no significant differences (P ＞ 0.05).The right number of group P (9.80 ± 2.39) were obviously decreased as compared with group C(13.30 ±2.00)(P ＜ 0.01),and there also had significant difference between group E and group C (P ＜0.05).In addition,the total reation time between group P ((82.30 ± 10.20) s) and group C ((67.70 ± 12.18) s) was significant difference(P ＜ 0.05).In HE staining,there were obvious changes in group E and P.In IHC,the expression of caspase-3 between groups C,E and P,there were no significant differences (P ＞ 0.05).Conclusion Single intraperitoneal injection of etomidate can make a transient effects for the rapid development period of rats ' ability of exploration,but have no obvious influence of the spatial cognition and learning and memory abilities.And etomidate lead less influence on newborn rat behavior and hippocampal tissue than propofol.