Abstract: To study the variation of serum glycyl-proline dipeptidyl aminopeptidase (GPDA) in chronic liver diseases and to evaluate its clinical diagnosis value. Serum GPDA levels of 131 patients of chronic liver diseases and 103 normal control subjects were measured by continuous monitoring method. The levels of serum alanine aminotransferase (ALT) were measured simultaneously. The Serum GPDA levels of all kinds of chronic hepatitis and liver cancer patients were higher than those of control group and the difference between them was significant (P<0.001) . The levels of GPDA of hepatocirrhosis patients with / without compensation and those of control group had no significant difference (P>0.05) . The ALT levels of chronic hepatitis and hepatocirrhosis patients were higher obviously than those of control group and the difference between them was significant (P<0.001) . The cases and times of ALT were higher than those of GPDA. There is some significance of serum GPDA for diagnosis of chronic hepatitis, but the sensitivity of GPDA is lower them that of ALT. There is some value of GPDA for diagnosis of liver cancer, but there is no value for diagnosis of hepatocirrhosis.