Introduction: Breast cancer is the most common cancer among women worldwide. Sulfotransferase plays an important role in the formation of estrogen which is usually conferred as a risk factor for breast cancer. The SULT1A1*2 polymorphism is likely to play an important role in the susceptibility to breast cancer. This polymorphism (G638A) in the sulfotransferase 1A1 (SULT1A1) gene may causes Arg213His amino acid change and consequently results in significantly reduced enzyme activity and thermostability.Materials and Methods: In this case-control study, we investigated the role of SULT1A1 G638A polymorphism in breast cancer patients. We genotyped 144 patients with breast cancer and 116 healthy control subjects, using a Polymerase chain reaction –Restriction Fragment length polymorphism (PCR-RFLP) method.Results: The frequencies of SULT1A1 G638G, G638A and A638A were 83.5%, 17.8%, and 1.4% in the breast cancer group and 89.5%, 4.0% and 0.0% in the control group. The results of our study indicate that the SULT1A1 G638A genotype showed 4.6 folds increased risk of breast cancer (p = 0.002).Conclusion: In conclusion, our results suggest that, SULT1A1 G638A variant is significantly associated with risk of breast cancer in south Indian women
