Our aim was to evaluate the association of genetic polymorphisms of immunoregulatory molecules with susceptibility to hepatocellular carcinoma (HCC). The polymorphisms in CTLA‐4 (−318 T/C, CT60 G/A), TNF (−238 G/A, −308 G/A) and IL10 (−592 C/A, −819 C/T) were genotyped by PCR and DNA sequencing. The functional relevance of the polymorphisms was examined by ELISAs, in vitro lymphocyte proliferation assay and cytotoxic assay. The CTLA‐4 −318 TC/TT, CTLA‐4 CT60 GG, IL10 −592 CA and −819 CT/TT variants, CTLA‐4 −318 T and IL 10 −819 T alleles were positively associated with HCC risk (P < .05). While TNF −238 AA variant, TNF −238 A allele were associated with decreased risk of HCC (P < .05). Furthermore, combinations of CTLA‐4 −318 TC/TT and TNF −238 GG/GA; CTLA‐4 −318 TC/TT and IL 10 −819 CC; CTLA‐4 −318 CC and IL 10 −819 CT/TT in patients with HCC were statistically significant (P < .05). Peripheral blood mononuclear cells (PBMCs) carrying −318 TC/TT genotypes exhibited significantly lower proliferation rates, decreased IL‐2, IL‐4 levels, fewer cytolytic activities and elevated TGF‐β levels. For IL 10 −819 C/T, the CC genotype was significantly associated with higher proliferation rate, decreased TGF‐β, IL‐10 levels and higher cytolytic activities (P < .05). For TNF −238 G/A, the AA genotype only had association with serum IL‐2, IL‐4 (P < .05). In addition, we also found that CTLA‐4 −318 T/C, IL‐10 −819 T/C variants, combinations of CTLA‐4 −318 CC with IL 10 −819 CT or TT, CTLA‐4 −318 TC or TT with IL 10 −819 CT or TT were associated with the severity of HCC. These findings suggest that CTLA‐4 −318 TC/TT and IL 10 −819 CT/TT could promote the pathogenesis of HCC, which might be related with down‐regulation of Th1/Th2‐type cytokines and/or up‐regulation of Th3‐type cytokines.