Our study demonstrated that UGT1A1 gene expression is decreased in breast cancer cases in comparison to controls in AA and EA female donors who have either the UGT1A1*1/*1, UGT1A1*1/*28, UGT1A1*28/*28, or the UGT1A1*28/*37 genotype. This evidence concerns the gene UGT1A1 and breast carcinoma.