Pseudorabies virus was injected into the wall of the urinary bladder and, following incubation times of 2, 3 and 4 days, central nervous tissue was processed immunohistochemically for the presence of virus. Longer incubation times resulted in more extensive spread of the virus. Infected neurons were initially found in the spinal cord (mainly lumbosacral) and, after longer survival times, in raphe nuclei, reticular area, pontine micturition center, locus coeruleus, red nucleus, hypothalamus, preoptic, and cortical areas. These data define a multisynaptic circuit of neurons whose ultimate output influences urinary bladder function.