Objective To investigate the correlation between the combination of smoking and the polymorphisms of cytochrome P450（CYP） 1A1-MspⅠ and glutathione S-transferase（GST） T1 genes and oral cancer. Methods The genetic polymorphisms of CYP1A1-MspⅠ and GSTT1 were detected by polymerase chain reaction（PCR） technique in peripheral blood leukocytes of 300 oral cancer cases and 300 non-cancer controls, and the correlation between smoking, the two metabolic enzymes genetic polymorphisms and oral cancer were analyzed. Results The frequencies of CYP1A1-MspⅠ（m2/m2） and GSTT1（-） were 38.33% and 69.33% in oral cancer cases and 21.00% and 44.33% in healthy controls respectively. Statistical tests showed significant difference in the frequencies between the two groups （P
