Abstract: Objective : The purpose of this study was to evaluate the value of fructose 1,6-diphosphate aldolase (FDP aldolase) in detected tumorous tissue damaged by Percutaneous Ethanol Injection(PEI) in patients of Hepatocellular Carcinoma(HCC). Methods : There were 18 patients with 24 tumor nodules treated by Percutaneous Ethanol Injection, Changes in serum levels of FDP aldolase activities were analyzed at different time after PEI treatment,and the levels of serum alpha -fetoprotein (AFP) were also measured. These indexes were compared. Results : Serum levels of FDP aldolase were increased (P<0.05) after the first PEI treatment and thereafter decreased just like the wave. After the eighth PEI, it came back to the levels of pre -treatment. Changes in serum levels of FDP Aldolase indicated tumor tissue necrosis in HCC. Serum levels of AFP were decreased after treatment, it also indicating adequate tumor tissue necrosis. Conclusions : The measurement of FDP aldolase activities in serum after PEI treatment is clinically useful to detect the degree of tumorous tissue damage,especially for the cases that AFP are negative.