Although, several polymorphisms have been described in the CYP1B1 gene, we have chosen in this exploratory study to evaluate the role of the CYP1B1 Val432Leu polymorphism in breast cancer susceptibility in Nigerian women since there is experimental evidence suggesting that the variant CYP1B1 432Leu allele exceeded the wild-type CYP1B1 432Val allele with respect to estrogen hydroxylation activities. This evidence concerns the gene CYP1B1 and breast carcinoma.