The doppel protein (Dpl) is a prion-like protein encoded by the gene PRND, which has been found downstream of the prion gene, PRNP, in human and mouse. This paper describes the isolation and structural organization of the bovine and ovine PRND genes, which are composed of two exons compared with the three of human and mouse. Intergenic distances between PRNP and PRND were covered by means of long-range PCR and found to be 16.8 and 20 kb, in cattle and sheep respectively. The 5' and 3' untranslated regions (UTR) were analyzed to identify transcription regulatory sequences and compared with those from the PRND and PRNP sequences published for other species. Three polymorphisms (R50H, N110H, and R132Q) were revealed in the cattle coding region; two synonymous substitutions (I12I, A26A) were found in sheep. None of the polymorphisms was significantly associated with either Bovine Spongiform Encephalopathy (BSE) in cattle or scrapie in sheep.