Objective To explore the value of serum monoethylglycinexylidide(MEGX)and branch chain amino acid/aromatic amino acid ratio(BCAA/AAA)in determining the liver reserve function in rats at different phases of hepatic injury.Methods Forty male Wistar rats were randomized into the experimental group and control group.Rats in the experimental group received subcutaneous administration of CCL4 with oil and those in the control group received the mixed solution of saline and oil.Serum MEGX and BCAA/AAA ratio were determined and common hepatic function tests and histological examinations of liver tissue were performed in all the rats at different phases of hepatic injury.Results The concentrations of serum MEGX decreased gradually with development of the severity in liver injury,which was in consistent with the liver histological change.Serum BCAA/AAA ratio could reflect the severity of liver injury,but it was less sensitive than serum MEGX.In the experimental group,the common liver functional parmeters were all abnormal and not in consistent with liver histolgical change.Conclusion Serum MEGX is more agreeable to liver histological change than serum BCAA/AAA ratio and common liver functional parameters.MEGX test can be used to concisely represent the liver histological change.