Alpha-methylacyl-CoA racemase (AMACR) is an enzyme involved in beta-oxidation of branched-chain fatty acids and bile acid intermediates. Recent works have revealed that AMACR is overexpressed in prostate cancer and functionally important for the growth of prostate cancer cells. Despite the recent interest in AMACR as a diagnostic marker for prostate cancer, little is known about the transcriptional regulation of AMACR in prostate cancer. To elucidate the regulation of the AMACR gene, a 2.3-kb fragment of its 5' flanking region was cloned into pGL3-Basic, then using tansfection and Dual-luciferase reporter assay, a preliminary analysis on promoter activity and function of this 2.3-kb sequence was carried out. This 2.3-kb fragment represented promoter activity that consistent with the expression level in LNCaP and PC-3 cells respectively. Transfection experiments of 5'-deletion mutants into LNCaP cells revealed a positive-regulatory region located between nucleotides -423 and -93 that may be responsible for AMACR transactivation in LNCaP cells. Cotransfection experiments revealed that promoter activity of this 2.3-kb sequence was down-regulated by C/EBPalpha, p53, NF-kappaB p50. And data from luciferase-based reporter assays suggest that the promoter function of AMACR is independent of androgen receptor-mediated signaling.