BACKGROUND The influence of chronic prostatitis on serum PSA level is well known. Whether it also influences potential new biomarkers of prostate cancer (PCa) has to be determined. We conducted a prospective study to evaluate the effect of chronic prostatitis on the PCa urinary marker PCA3. METHODS. Included were 38 patients, mean-aged of 37.5 years, with clinical suspicion of chronic prostatitis. A simplified version of the Meares-Stamey four-glass localization test was performed and urine specimens were collected for cytological analysis and culture. A postprostatic massage urine sample was used for the urinary PCA3 test. RESULTS. Four patients had an eventual diagnosis of urethritis and all had a PCA3 score less than 5. Among the remaining 34 patients, 7 had bacterial chronic prostatitis (NIH II prostatitis), 11 had abacterial chronic prostatitis (NIH IIIa), and 16 had non inflammatory prostatodynia (NIH IIIb). All these patients had a PCA3 score less than 28, that is, under the cutoff of 35, which is commonly used for prostate cancer diagnosis. Patients with NIH category IIIa prostatitis had significantly higher number of leukocytes and red cells as well as prostate cells in urine samples but their PCA3 scores did not differ from those of other prostatitis patients. CONCLUSION. In this study, NIH II and III chronic prostatitis did not influence the PCA3 score. Our results suggest that increased PCA3 score is unlikely to be explained by the sole chronic prostatitis and warrants prostate biopsies to eliminate prostate cancer. Prostate 72: 549-554, 2012. (C) 2011 Wiley Periodicals, Inc.