This paper describes the first identified chorionic PAGs in the European bison (Eb), named EbPAGs, predominantly expressed during early and mid-pregnancy (45-120 day post-coitum; dpc). Many EbPAGs were extracted from various cotyledonary tissues, precipitated, chromatographed (DEAE and VVA: Vicia villosa agglutinin), electrophoresed (1D- and 2D-PAGE), analysed by heterologous (cross-species) Western blotting and then micro-sequenced by Edman degradation. Finally, twelve selected VVA-purified isoforms (Ip 3.7-7.4) were entirely characterised. Nine identified NH(2)-terminal micro-sequences were found to be PAGs. On 45 dpc, three identified forms were named: EbPAG(67AkDa) (RGSNLTHPLRNIGDLFYVGN), EbPAG(55BkDa) (RGSNLTHPL) and EbPAG(50CkDa) (SQISLRGSNLTI). On 60 dpc, the next three forms were named: EbPAG(71DkDa) (RGSNLTIHPLRNIIDLFYVG), EbPAG(55EkDa) (RGSNLTHPLRNI) and EbPAG(50FkDa) (SQISLRGS). On 120 dpc, three other forms were named: EbPAG(71GkDa) (RGSNLTHPLRNIRDLFYVG), EbPAG(60HkDa) (RGSNLTTHPLRNIKDLVVYM) and EbPAG(50IkDa) (SGSNLTTV). These EbPAG ((A-I)) sequences are unique, as they are not identical to any other PAGs purified previously in related species of the Bovidae family. However, the EbPAGs (A-I forms) have some sequence resemblance to internal sequences of various full-length polypeptide PAG precursors (in silico translated from cloned cDNAs) identified in domestic cattle. Three other novel native isoforms (J1, J2 and K): EbUPG(45kDa) J1 (SKDNYKNYIPLIVPFAT), EbUPG(45kDa) J2 (SKDNQKNYIPLIVPFAT) and EbUPG(76kDa) K (SPEFTV), were temporarily named 'unknown placental glycoproteins' (UPGs), due to their efficient VVA-purification (specific for glycoproteins only) and a lack of considerable consensus to previously sequenced placental glycoproteins in the Bovidae family. This is the first study identifying NH(2)-terminals of multiple/diverse EbPAGs and some EbUPGs purified from the synepitheliochorial cotyledonary placenta of the endangered Bison bonasus (Red List).