Cloned pseudorabies virus (PRV) sequences representing over 80% of the viral genome were radiolabeled and individually hybridized to nucleic acid in the trigeminal ganglia of acutely and latently infected swine. In acutely infected animals, all cloned probes hybridized to PRV RNA and DNA. In contrast, during latency transcription was found to be limited to a selected region, corresponding to the IE gene, analogous to that of two other alpha-herpesviruses. Viral DNA was not detected in latently infected neurons by in situ hybridization.