CYP17 gene encodes the enzyme cytochrome p450c17alpha, which mediates two steps in the steroid biosynthesis pathway. Steroid hormones are believed to play a key role in the etiology of prostate cancer. A polymorphic T-->C transition in the 5' promoter region of CYP17 creates an additional Sp1-type (CCACC box) promoter site (allele A2). We have evaluated the genotypic and allelic distribution of this polymorphism among 92 prostate cancer patients in order to assess risk by comparison with a population-based series of 200 healthy individuals from Brazil. Our results provide no evidence for an association between prostate cancer risk and CYP17 T/C polymorphism.512831