Objective: To study the gene polymorphisms of GSTT1 and GSTM1 in nasopharyngeal carcinoma (NPC) patients and controls in an incidental area to evaluate the relationship between specific genotype and genotype combinations of these polymorphisms with the risk of NPC.Methods: Cases and controls all came from the Southwestern Guangxi. DNAs were extracted from their WBC. PCR technique was used to calculate the deletion rate of the two detoxific enzyme genes. Results: In this high risk area of NPC, the residents had high level deletion rates of 47.4% (64/135) M1 and T1 40.7% (55/135). The deletion rates were even higher in NPC patients, 61.5% (56/91) for M1 and 59.3% (54/91) for T1 respectively. There were statistical significances compared with control, P＜0.05 and P＜0.01 for M1 and T1 respectively. The difference was more significant in terms of combined M1 and T1 deletion between patients and controls x2=12.533, P=0.002.Conclusion: The combined deletion of detoxific enzyme genes GSTM1 and GSTT1 may be an important genetic susceptible factor for NPC in Guangxi.