The endemic taxa of spiders (Araneae) in the Balkan peninsula are represented by 348 species included in 30 families. Countries with the highest number of recorded endemic species are Greece (115), Croatia (68), Bulgaria (55), Bosnia (41), Crete (46). The distribution of the endemic spiders in the main geographic systems of the Balkan peninsula shows that they are best represented in the Pindus region - 150, Dinaric region - 145, Tracian-Macedonic region - 52, Balkanid region - 14, Danubian region - 4 and North Dobrudzha with 4 species. The largest proportion of endemics was encountered mainly in the mountains and islands, where they inhabit caves - 159, woodlands - 139, coastal sites - 48 and high altitude zones - 20 species. The extreme richness of troglobitic spiders in the Dinaric region (96) leads to the assumption that this was a major center of speciation and evolution of species. The same can be said for the forest of the Pindus region (74) and for the highest mountains (Rila, Pirin) of the Tracian-Macedonic region, where are found the greatest number of high altitude elements (15). The phenomenon can be regarded as a result of the relative isolation of the mountains compared with the lowland areas, in the context of paleo-environmental changes since the Pliocene. The high percentage of endemic spiders (25%) suggests an important process of autochthonous speciation. So the Balkan Peninsula can be considered as a main center of speciation in Europe.