Human prostate-specific antigen (PSA) gene has been shown to be regulated by androgen, and its androgen response element (ARE) has been located at about －170. To determine whether the androgen inducion of the gene was affected by upstream sequence of ARE, different natural and mutated DNA fragments of PSA promoter were linked to the CAT reporter gene respectively, and different pBLCAT3-PSA plasmids were constructed and used for transfection in human prostatic cancer cell line PC-3. The results indicated that a 15 bp segment of RF15 (－340～－326) could cooperate with ARE in maximal androgen induction significantly. The bandshift assay showed that some nucleic regulatory protein from human prostatic cancer cell line LNcap and PC-3 could bind to RF15 DNA fragment. And the protein ability to bind to RF15 was influenced by Zn²⁺. The results suggested that the RF15 may be a new regulatory sequence in the PSA promoter region. The regulatory protein, which binds to the RF15 sequence, may enhance the androgen induction via interaction with androgen receptor.