Aim: To investigate the expression change of NK cells receptor NKG2D from human peripheral blood in patients with primary carcinoma of liver and study the relationship between NKG2D expression and cytotoxicity of NK cells. Background/Aims: Lens culinaris agglutinin-reactive alpha-fetoprotein (AFP-L3) is a specific protein produced by hepatocellular carcinoma(HCC), which is more valuable than AFP in the diagnosis of HCC. Aptamers are oligonucleotide ligands binding to target molecules sensitively and specifically, which are screened from a great capacity of synthetically oligonucleotide library by systematic evolution of ligands by exponential enrichment (SELEX). Our aims were to select the aptamers against AFP-L3 from a self-designed ssDNA library for potential application in diagnosis of HCC. Methods: A random ssDNA library and its corresponding primers were designed and synthesized. Aptamers against AFP-L3 were selected by SELEX. Individual aptamers were separated by polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) analysis and characterized. Results: A ssDNA library of 78 nucleotides with 40 random nucleotides in middle were designed and used for the selection. The binding rate of library against AFP-L3 was increased from 5.1% to 48.2% after 13 round selection. Seven aptamers (S1 to S7) were isolated, and their sequences in random region and secondary structures were different from each other. All aptamers could bind AFP-L3 in a different extent, and the dissociation constants of S4 and S7 are 650nmol/L and 132nmol/L. Conclusions: Aptamers for AFP-L3 are successfully screened out and could bind AFP-L3 specifically. Methods: Flow cytometry was used to determine the number of NK cells and the expression of NK cells receptor NKG2D from human peripheral blood in patients with 20 case primary carcinoma of liver 23 case hepatitis B cirrhosis 20 case hepatitis B and 20 healthy cases and enzyme mark instrument was used to detect cytotoxicity of NK cells in all cases. Results: killing rate of NK cell for K562 cell,NKG2D expression level of NK cells, and the number of NK cells in the patients with primary carcinoma of liver decreased significantly P<0.05 compared with those in the healthy subjects and hepatitis B group ,And decreased a little compared with those in the hepatitis B cirrhosis (P>0.05).The activity of NK cells showed a obvious positive-correlation with the number of NK cell and expression level of NK cell receptor NKG2D. Conclusion: The cytotoxicity of NK and the NKG2D expression of NK cells decreased significantly from human peripheral blood in patients with primary carcinoma of liver .The activity of NK cells is closely related to the NKG2D expression level of NK cells. enhancing the NKG2D expression level of NK cell may provide a new idea for Adoptive immunotherapy of primary carcinoma of liver. and alpha-fetoprotein AFP in serum and tissues for primary hepatic cancer(PHC). Methods: Sixty-six PHC and 32 cirrhotic patients were enrolled. In PHC patients,male /female was 48:18, age was 55.4 ± 9.91.of them, 16 patients were defined as stage a-a. In cirrhotic patients, male /female was24:8, age was 53.3 ± 5.81. SerumGPC3 was detected using ELISA. Serum AFP was detected using electrochemiluminescence. The hepatic expressions of GPC3 and AFP were measured using immunohistochemistry in 21 PHC and 6 cirrhotic patients. Results: The cutoff value of AFP diagnosis for PHC was 400 g / L or more, AFP positive in PHC patients was 28.8% (19/66); The cutoff value of GPC3 diagnosis for PHC was 300ng / L or more, GPC3 positive was in 47.0 % (31/66), P = 0.031. In a-a stage PHC patients,the positive of GPC3 and AFP was 62.5% (10/16), 0(0/16), respectively,P = 0.000. In serum AFP negative or positive patients, the positive of GPC3 was 46.7% (14/30) , 47.2% (17/36), respectively,P = 0.964. The relationship between GPC3 with age, sex, Child-pugh grade, HBV infection, tumor size and metastasis were not observed.The positive expression of GPC3 and AFP in hepatocellular carcinoma tissue was 85.7% (18/21), 4.8% (1 / 21), respectively, P = 0.000. Neither GPC3 ,nor AFP in the paracarcinomatous and cirrhotic tissue, was expressed. Conclusions: Diagnosis of Glypican-3 protein for primary hepatic cancer is superior to AFP.GPC3 can be regared as a early marker to diagnosis PHC. 