European Bison (Bison bonasus L.), the largest herbivorous mammal in Europe, was distributed in western, central and southeastern Europe in the past. Just after the first world war, at the beginning of 20th century, the species extinct in the wild. Only few animals survived in private breeding herds and zoo. International effort to protect the species was coordinated by International Society for the Protection of European Bison (ISPEB), established in 1923 in Germany to maintain of the species' genetic purity by planned breeding and distribution, followed by introductions to large forest complexes. For this purpose a European Bison Pedigree Book (EBPB) -- a register of all European bison living in the world -- was created. In end of 70thes number of animals crossed/reached a minimal population size -- 2000 individuals and the species was declared as saved one. Following this, interests of breeders decreased and financial support was limited and, therefore, total EB population decreased; serveral diseases appeared as important factor. The species was again under a threat and since 1988 it was again included into IUCN Red list of Endangered Species as a vulneralble (D) and since 1996 as endangered species (EN). Two genetic lines are distinguished in recent populations: the Lowland line (B. b. bonasus) and the Lowland-Caucasian line (B. b. bonasus x B. b. caucasicus). There are no surviving pure-bred populations of B. b. caucasicus. Total global number of European bison (registered in EBPB 2010 as ‟pure blood bison“ in the year 2010) is about 4430, including about 2956 animals in free and semi-free populations. The data of genealogical analyses indicate that the world population of European bison is highly inbred. IUCN 2011 registered the species as vulnerable one, it means that the species is saved from extinction. But still it is endangered by limited species gene-pool. [ABSTRACT FROM AUTHOR]