Loss of FAS (CD95) expression is a common feature of malignant transformation, which has been related to loss of epithelial cell differentiation and loss of sensitivity to apoptosis. We investigated the potential association between FAS promoter polymorphism and the genetic susceptibility to the Epstein-Barr virus (EBV)-related nasopharyngeal carcinoma. The in vivo functional significance of the FAS polymorphism was investigated by assessing the correlation between FAS genotypes and the presence of autoantibodies to cytoskeleton and nuclear antigens frequently detected in nasopharyngeal carcinoma. We determined the FAS polymorphism distributions by RFLP-PCR in 170 patients with nasopharyngeal carcinoma and in 224 sex and age-matched controls. We used ELISA and the immunofluorescence analysis to characterize the presence of IgG autoantibodies to the cytoskeleton and nuclear proteins in patients' sera. A significantly increased risk of nasopharyngeal carcinoma was associated with heterozygote FAS-A/G (OR=2.00, P=0.001) and homozygote FAS-G/G (OR=3.19, P=0.0001) variants. The increased frequency of FAS-G/G genotype is correlated with the presence of anti-nuclear autoantibodies in patients with nasopharyngeal carcinoma (P=0.0298). Our results demonstrated that FAS promoter polymorphism was significantly associated with the nasopharyngeal carcinoma in Tunisians. The anti-nuclear autoantibodies induction was also found to be related to FAS polymorphism. The FAS promoter polymorphism associated not only with the increased risk of nasopharyngeal carcinoma in Tunisians but also with immune response deregulation observed in this cancer.