Objective To detect the gene expression of PCA3 and PSA in peripheral blood and urine simultaneously to investigate whether PCA3 combining PSA gene could become new markers for diagnosis of Pca. Methods From June 2009 to December 2009,the initial urine after prostatic massage and the peripheral blood specimens were collected from 37 patients with PCa and 68 patients with BPH that were pathologically confirmed,g patients with urinary stone were used as normal control,the expression of PCA3 and PSA mRNA of mononuclear cells in urine sediments and peripheral blood were detected by fluorescence real-time quantitative PCR,with β-actin mRNA as internal control. Results The sensitivity and specificity of the expression of PCA3 mRNA in peripheral blood for diagnosis of prostate cancer were 48.6％ and 100％ respectively.ROC curve analysis was performed for the PCA3 score and the area under the ROC curve was 0.908.Using 64.6 as the cutoff,the sensitivity was 81.1％ and the specificity was 86.8％.In group with serum tPSA value ＜4 pg/L,the positive rate and negative rate of urinary PCA3 score for diagnosing prostate cancer were 80％ (4/5) and 89.4％ (20/22) respectively.In group with serum tPSA value 4 - 10 μg/L,the positive rate and negative rate of urinary PCA3 score were 66.7％ ( 2/3 ) and 84.2％(16/19) respectively.In group with serum tPSA value ＞ 10 μg/L,the positive rate and negative rate of urinary PCA3 score were 82.8％ (24/27) and 81.5％ (22/27) respectively.The sensitivity of simultaneous detection of PCA3 mRNA in peripheral blood and urinary PCA3 score was 86.5％. Conclusions The expression of PCA3 mRNA in peripheral blood was a specific marker for the diagnosis of PCa.The simultaneous detection of PCA3 mRNA in peripheral blood and urinary PCA3 score could increase the sensitivity for the diagnosis of PCa.