Patients with an elevated serum total prostate-specific antigen value or abnormal digital rectal examination results are at risk of having prostate cancer and should undergo prostate needle biopsies. However, approximately 60% of them will have a negative prostate biopsy result. Therefore, further biopsies are recommended for young patients at risk of prostate cancer with a positive rate of 20-40%. Biomarkers are required in order to avoid unnecessary biopsies. The PCA3 gene product is specifically overexpressed in prostate tumor cells, and modern molecular biology techniques allow us to use a specific test for this gene in order to select patients who have a high risk of having prostate cancer. Literature reviews of the gene product, as well as the first clinical results of the Progensa PCA3 test, are presented.