Objective：To study the protective effects of acetyl-L-carnitine（ALC） on ischemic brain injury in rats and oxygen-glucose deprivation（OGD） induced cells as well as the possible mechanisms. Methods：Using the table of random number，SD rats were di－vided into three groups：sham group，model group and ALC group. ALC and an equal volume of phosphate buffer were injected intraperitoneally for ALC，model and sham groups respectively at 24 h before cerebral ischemia rat model was made. TTC（2，3，5-Triphenyltetrazolium chloride） staining was used to assess the effects. In vitro，PC12 cells were divided into normal group，model group and ALC group. ALC was given at 24 h before OGD model being made. Cell viability，apoptosis and necrosis were analyzed using MTT assay，TUNEL，SYTOX staining respectively. Activities of adenosine triphosphatase（ATPase） and superoxide dismutase（SOD） as well as maleic dialdehyde（MDA） content were also detected. Results：After the pre-treatment of ALC，the infarction size was obviousely reduced（P<0.05）；in vitro，the cell viability，activities of SOD and ATPaes were increased，while the content of MDA，percentage of apoptotic and necrotic cells were decreased compared with those in OGD group（P<0.05）. Conclusions：These results suggested that ALC has protective effects on ischemic injury rats and OGD induced PC12 cells. The effects may be associated with the improvment of cell antioxidant capacity and energy metabolism as well as the supression of necrosis and apoptosis.