The poor specificity of diagnostic strategy for prostate cancer (digital rectal examination and seric PSA) induces both a great number of useless prostate biopsies and diagnosis of non evolutive cancers. A urinary test (Progensa PCA3(R), Gen-Probe) measuring the expression of PCA3, a prostate cancer-specific gene, has recently be proposed to indicate re-biopsy. The aim of this prospective study was to evaluate diagnostic value of urinary PCA3 test for prostate cancer. In the urines of 245 patients submitted to prostate biopsy, expression of the PCA3 gene was measured and reported to that of PSA to calculate PCA3 score using a method amplifying and detecting RNA. Patients with informative samples (98%) were classified depending of the presence (n = 126) or absence (n = 1 14) of cancer tissue on biopsies. The median PCA3 score was significantly higher in the group with positive biopsies (p < 0.0001). Area under ROC curve was 0.70 for PCA3 as compared to that of PSA (0.53) and free/total PSA ratio (0.65). At the best threshold of 38, PCA3 test had a 59%-sensitivity and a 72%-specificity, as compared to 66% and 32% for total PSA (threshold 4 ng/mL) and 81% and 28% for free/total PSA ratio (threshold 25%). These performances were maintained in patients with seric PSA within the grey zone (4-10 ng/mL) and those with previous prostate biopsies. This study confirms the clinical value of PCA3 urinary test in helping decision for biopsies in patients with suspected prostate cancer.