Phospholipase Cbeta3 (PLCbeta3) is a member of the family of phospholipase C isoenzymes, a second messenger system that plays an important role in initiating receptor-mediated signal transduction in response to extracellular signals. Using RNA in situ hybridization we showed that in the embryonic rat nervous system, PLCbeta3 is expressed in dorsal root ganglia (DRGs) and the trigeminal ganglion. Characterization of the hybridization signal in the adult rat nervous system revealed that PLCbeta3 expression is confined mainly to small-sized DRG neurons. In non-neuronal tissues, PLCbeta3 is expressed by cells of epithelial origin, such as skin and the mucous lining airways and the gastrointestinal canal, and in lung and thymus.