Abstract： Objective To investigate the role of aldehyde dehydrogenase 2 (ALDH2) in the protection against tubular epithelial cells (TEC) ischemia/reperfusion (IR) injury induced by pretreatment with ethanol.Methods Mouse primary cultured TECs were pretreated with 50 mM ethanol 3 h before simulation of in vitro IR.Lactate dehydrogenase (LDH) release was assessed to evaluate the protection of ethanol pretreatment on IR injury.Thereafter,TECs were transfected with a negative control siRNA (NC) or an ALDH2-siRNA. The ALDH2 protein levels and ALDH enzymatic activities were assessed 48 h after transfection.Ethanol pretreatment and in vitro IR were performed on those transfected TECs.LDH release was assessed to evaluate the role of ALDH2 in the ethanol pretreatment-induced protection against IR injury.Results Ethanol pretreatment significantly reduced the LDH release in TECs upon IR insult.As compared with NC group and INTERFERin group,the ALDH2 protein levels were decreased by 82.1％,ALDH enzymatic activities were decreased hy 67.3％,and the protective effect induced by ethanol pretreatment was almost completely abrogated in ALDH2-siRNA group.Conclusion Ethanol pretreatment protects TECs against IR injury through ALDH2 dependent pathways.