Intracellular virus specific polypeptides of pestivirus, border disease virus (BDV) in bovine turbinate cells were analysed by radio-immunoprecipitation with specific antisera. Eleven viral polypeptides with molecular weights of 220, 165, 118, 84, 66, 58, 55, 53, 45, 37 and 31 kDa, respectively, were detected in infected cells. Of these, the 165, 118, 84, 66, 58, 55, 53, 45 and 31 kDa proteins were found to be glycosylated. Comparative studies indicated that the polypeptides induced by BDV share many antigenic epitopes with those of the polypeptides induced by bovine viral diarrhea virus (BVDV), a serologically related virus of the same genus, pestivirus. The polypeptide profile of BDV appeared to be more similar to that of the noncytopathic BVDV strain NY1 compared to that of cytopathic BVDV strains NADL and Singer. Peptide mapping analysis of homologous polypeptides from BVDV and BDV confirmed their structural relatedness.