We have studied the contribution of the nervous system on experimentally induced urethral inflammation in the rat. Urethral inflammation was induced by inserting latex strips into the urethra. The effects of different experimental procedures was assessed by using a 4-graded inflammation scale based on the histological findings. Attenuation of urethral inflammation was produced by administration of capsaicin at birth. A more complete attenuation was produced by sympathectomy prior to application of the latex strip. Urethral inflammation was also severe in the spontaneous hypertensive rat. Injection of morphine into the third ventricle of the brain significantly reduced the experimentally induced urethral inflammation. These data taken together indicate that the sensory and postganglionic innervation of the urethral mucosa as well as the central nervous system is critically involved in the inflammatory reaction of the urethra following exposure to latex strips.