This work sums up the results of small terrestrial mammal´s research since 1974 till 2010. Species richness of small mammals is different in various altitudinal zones of Slovakia. There was found 18 species of small mammals in the lowest present altitude (to 499 m a.s.l.), species richness achieved the maximum (19 species) in the next altitudinal zone (from 500 to 699 m a.s.l.), then number of species declined to 17 species (from 700 to 899 m a.s.l.) and in the zone from 900 to 1,099 m a.s.l. increased to 18 species. The number of species decreased to 17 in altitudinal level from 1,100 to 1,299 m a.s.l., followed by other continuing decrease of 14 species (from 1,300 to 1,499 m a.s.l.) and 11 species in the highest altitude (from 1,500 to 1,750 m a.s.l.).