Colorectal cancer is caused by both genetic and environmental factors. We investigated the association between polymorphism of cytochrome P4501A1 (m1) and glutathione-S-transferase M1and colorectal cancer in 40 cases and 20 controls using PCR for GSTM1 and PCR-RFLP for CYP1A1 (m1) polymorphism detection. Our results showed that no statistically significant association existed between GSTM1 null genotype (OR=0.658, 95%CI= (0.217-1.997) or CYP1A1 (m1) genotype (OR=0.333, 95% CI= (0.078-1.416) and colorectal cancer.