BACKGROUND The study aimed to investigate the expression of brain natriuretic peptide (BNP) and natriuretic peptide receptor A (NPR-A) in L6-S1 dorsal root ganglia (DRG) in a rat model of chronic nonbacterial prostatitis (CNP). MATERIAL AND METHODS One hundred specific pathogen-free (SPF) male Sprague-Dawley rats were randomly divided into a control group (N=50) and a study group (N=50). The control group underwent prostatic injection of 0.1 ml of normal saline on days 3, 7, 10, 14, and 28. The study group, or rat model of CNP, underwent prostatic injection of 0.1 ml of complete Freund's adjuvant on days 3, 7, 10, 14, and 28. At the end of the study, the rats were euthanized, and the prostate tissues and L6-S1 DRG were removed. Histology was performed on the prostate tissue from the rats in the study group and control group. Real-time fluorescence-based quantitative polymerase chain reaction (PCR) and Western blot were used to study the expression of BNP and NPR-A mRNA and protein in the DRG from the rats in the study group and control group. RESULTS In the rat model of CNP, the expression of BNP and NPR-A were significantly increased in L6-S1 DRG compared with the controls. CONCLUSIONS In a rat model of CNP, the increased expression of BNP and NPR-A in L6-S1 DRG may have a role in pain signaling pathways associated with chronic prostatitis.