Objective：To investigate the expression of hepatic apolipoprotein M (apoM) mRNA and serum apoM during early stage of hepatic ischemia reperfusion injury in rats. Methods：Rat models of hepatic ischemiareperfusion injury (IRI) were established. Forty healthy male SD rats were randomly divived into five groups(each group containing eight rats)：Shamoperation group(control); IRI groups, animals experienced 1 hr ischemia and then followed by various reperfusion intervals(0.5,1.0,2.0 and 3.0 hrs, respectively). Results：Serum alanineaminotransferase (ALT) levels and the liver injury degree histologically were increased with the prolongation of hepatic reperfusion time. The apoMmRNA level in liver was markedly decreased in the group that had reperfusion for 0.5hr compared to the sham group. However, it increased gradually in groups that had reperfusion for 1hr to 3hrs. Serum apoM protein level showed a similar tendency with apoMnRNA, but it increased after reperfusion for 2 hrs. Conclusions：It is concluded that apoM expression pattern shows rapid and significant changes during hepatic ischemiareperfusion injury, which suggests that apoM might have the characteristic of acute phase reactive protein.