The spinal and brain neurons that innervate the rat prostate were identified using the transneuronal tracing technique. Three groups of rats were prepared: (1) nerve intact, (2) bilateral pelvic nerve cut and right hypogastric nerve cut and (3) bilateral hypogastric nerve cut and right pelvic nerve cut. Pseudorabies virus (PRV) was injected into the ventral prostate on the left side. After 2-4 days, the rats were perfused transcardially under deep anesthesia and the spinal cord and brain removed. PRV-labelled cells were identified using immunohistochemistry. After 3 days survival, sympathetic and parasympathetic preganglionic neurons were labelled with PRV. In addition, spinal interneurons were found in the dorsal gray commissure (DGC) of T13-S1. Rats with only one hypogastric nerve intact resulted in spinal labelling of sympathetic preganglionic neurons in the DGC and ipsilateral intermediolateral cell column (IML). In addition, many spinal interneurons were found from L1 to L6 in the medial gray. Rats with only one pelvic nerve intact displayed PRV-labelled cells in the parasympathetic preganglionic nucleus ipsilateral to the injection site. Spinal interneurons were present in the region of the IML and in the medial cord. In the brain, areas predominately labelled with PRV included the nucleus gigantocellularis and paragigantocellularis, raphe magnus, raphe pallidus, A5, Barrington's nucleus, central gray, ventral tegmental area, the paraventricular nucleus of the hypothalamus, lateral hypothalamus and medial preoptic area. These data demonstrate the sympathetic and parasympathetic spinal circuits and demonstrate the overlap of supraspinal innervation of the spinal interneurons.