Abstract: Objective To study the effect of manganese(Mn)on long-term spatial learning and memory capability in rats.Methods Fifty male Sprague Dawley rats were randomly assigned to five groups:normal saline(Group A), Mn²⁺ 2.5mg/kg(Group B),Mn²⁺ 5mg/kg(Group C),Mn²⁺ P> 10mg/kg(Group D),and Mn²⁺ 20mg/kg(Group E).Each experimental group consisted of 10 animals.Morris water maze was used to examine the meanlatency,path length,and the number of plat form area crossing of the rats.Results In Morris water mazetest,significant increases were found in meanla tency,path length,and the number of plat form area crossing in the groups(F=7.813,P=0.000;F=81190,P=0.000;F=31461,P=0.000).Significant increases were found in the meanlatency of groups B,C,D and E compared with that of group A(P<0.05).There was an obvious increase in the pathlength in the groups C,D and E compared with group A (P<0.01).Compared with group B,there were significant increases in the meanlatency in group D and E(P<0.05)and in the number of plat form area crossing in the groups C,D and E(P<0.01).Conclusion Manganese can affect spatial learning and memory ability in rats.