BACKGROUND Mechanisms, other than gene amplification, leading to overexpression of AR in androgen ablation-resistant prostate cancer remain unknown and could include genetic alterations in the promoter or untranslated regions (UTR) of the AR gene. MATERIALS AND METHODS DNAs from five prostate cancer cell lines, 19 LuCaP xenografts, 44 clinical tumors, and 36 non-malignant controls were used for screening mutations in the upstream regulatory region, promoter and the 5'- and 3'-UTRs of the AR gene with denaturating high performance liquid chromatography (DHPLC) and sequencing. RESULTS Ten different sequence variations were found in prostate cancer cell lines and xenografts. However, none of them were recurrent or were found in clinical prostate cancer specimens or in normal controls. CONCLUSIONS Recurrent mutations in the promoter or UTRs of AR seem to be rare, and thus not likely mechanisms for the increased expression of the gene in the androgen ablation-resistant prostate cancer.