In consideration of the role of ICOS, CD28 and CD80 genes in tumor immunity, we chose ICOS rs4404254 T>C, rs10932029 T>C, CD28 rs3116496 T>C and CD80 rs7628626 C>A SNPs to explore their potential roles in the etiology of HCC. This evidence concerns the gene ICOS and hepatocellular carcinoma.