ObjeCtive:To study the antimalarial effects and mechanisms of artemisinin (Qinghaosu in Chinese,QHS) on mitochondda in mice infected with Plasmodium berghei.Methods:A total of 108 C57 mice infected with Plasmodium berghei were randomly divided into 3 groups by weight:the control group,200 and 400 mg/kg QHS groups.The two QHS treatment groups were further divided into 4 sub-groups with 12 animals each time according to the treatment time,0.5,1,2,and 4 h.Normal saline was intragastrically (i.g.) administered to the control group.The other two groups received different doses of QHS by i.g.administration.Animals were treated once with QHS for different detection time as follows:0.5,1,2,and 4 h.The mitochondrial energy metabolism,oxidative damage,membrane potential,and membrane permeability and other indexes were detected.Results:After administration of 200 and 400 mg/kg QHS,adenosine triphosphate (ATP) levels in Plasmodium and its mitochondria were reduced (P＜0.05),the levels of reactive oxygen species (ROS) and malondialdehyde (MDA)were increased (P＜0.05),and the activity of superoxide dismutase (SOD) was also increased (P＜0.05).At the same time,the membrane potential of the mitochondria was reduced and the degree to which the membrane permeability transition pore was opened was irreversibly increased (P＜0.05).Conclusions:Mitochondria in Plasmodium were the targets of QHS,which can adversely affect mitochondrial energy metabolism,oxidative damage,membrane potential,and membrane opening,and ultimately exert an antimalarial effect.