The last four decades have seen significant increase in the incidence of non-Hodgkin lymphoma (NHL) as a possible result of increasing environmental carcinogens exposure. Based on the increasing evidence for the association between carcinogen-exposure-related cancer risk and xenobiotic gene polymorphisms, we have undertaken a hospital based case-control study on xenobiotic gene polymorphisms in Saudi individuals with a diagnosis of diffuse large B-cell lymphoma (DLBCL). Polymorphisms in five genes (CYP1A1, GSTT1, GSTP1, GSTM1, and NQO1) were characterized in 182 individuals with DLBCL and 513 normal controls using PCR-RFLP method. The CYP1A1*2C (p = 0.011, OR: 6.62, and 95% CI: 1.56-28.10), GSTT1 null (p < or = 0.001, OR: 11.94, 95% CI: 7.88-18.12), and GSTP1 TT genotypes (p = 0.017, OR: 3.42, 95% CI 1.26-9.38) demonstrated significant association of DLBCL risk. None of the other alleles tested for proved to be significant indicators of DLBCL risk. Our findings suggest that polymorphisms of xenobiotic metabolizing enzyme genes may modify the individual susceptibility to develop DLBCL in Saudi Arabian population.