Interindividual differences observed in the metabolism of xenobiotics have been attributed to the genetic polymorphism of genes, which code for enzymes involved in detoxification. This genetic variability seems to be associated with the individual's susceptibility to certain cancers, including nasopharyngeal carcinoma. In this study, we have investigated the genotypic frequencies of DNA polymorphisms of two detoxification's genes: the gluthatione-S-transferase (GST) and the N-acetyl transferase 2 (NAT2). The study has included 45 patients with nasopharyngeal carcinoma compared to 100 healthy Tunisian controls. The presence of the GSTM1 null and GSTT1 null polymorphism was screened by using a multiplex PCR procedure. A PCR-RFLP method was used to detect polymorphism for the most common alleles of the NAT2 gene. Allelic frequencies between the two groups were compared using a chi2 test and odds ratio with 95% confidence intervals were calculated. The results indicate that the genotypic frequency of GSTM10/0 between controls and patients was significantly different. This genotype confers an increased risk of nasopharyngeal carcinoma (Odds Ratio = 2.12, [0.64-4.7]). However, genotypic frequencies of NAT2*6/NAT2*6 were significantly higher in the group of nasopharyngeal carcinoma patients. The calculated Odds Ratio showed an association between this genotype and nasopharyngeal carcinoma. In conclusion, the increase of nasopharyngeal carcinoma risk in Tunisia seems to be associated with GSTM10/0 and NAT2*6/6 genotype.