Abstract: Objective : To study the value of quantitative determination of hepatoma -associated glycylproline dipeptidyl aminopeptidase (GPDA -F) in the diagnosis of primary hepatic carcinoma(PHC). Methods : GPDA-F was separated by polyacrylamide electrophoresis and then quantified by scanning. Serum GPDA-F, alanine aminotransferase (ALT) and alpha -fetoprotein (AFP) were simultaneously measured in PHC and other liver diseases. Relationships between GPDA-F activities and tumor sizes, AFP concentrations as well as ALT activities were analyzed. The values of quantitative and qualitative determinations of GPDA-F for the diagnosis of PHC were compared. Results : GPDA-F activities were significantly higher in PHC than benign liver diseases (P<0.01). GPDA-F activities were over cut-of± in 60.0% PHC with tumor sizes less than 5cm and 71.4% PHC with negative AFP(<50μg/L).The specificity and accuracy of GPDA-F/ALT were higher than those of GPDA-F quantification for the diagnosis of PHC. Conclusion : Quantitative determination of GPDA-F may improve its value for the diagnosis of PHC.