Colorectal cancer is the third most common cancer and the second leading cause of cancer deaths in the world. Risk factors such as obesity, low-fiber diet, sedentary, and alcohol have been implicated in the development of this cancer. Cells have many mechanisms in place to fight malignancy and cancer, one of which is the detoxification system that protect the cell against DNA damage. One of the essential components of this system is the glutathione s-transferase. In this study, the genotype of region -69 promoter of this gene in 150 colorectal cancer patients and 150 healthy people was investigated by the RFLP method. T/T genotype is significantly associated with colorectal cancer (P = 0.0001), C/T genotype did not show a significant association with colorectal cancer and its frequency was not significantly different in both healthy and patient groups (P = 0.074), Most genotypes in the two groups were homozygous C / C and did not show a significant association with colorectal cancer.