Australia is the smallest continent, naturally isolated from other continents and because of that there have evolved special animal and plant species. These kinds of species have small living space and they are called endemics. Endemics are divided by origin and by age on paleoendemics (relicts) and neoendemics (youngs). It has been described 147579 species in Australia and endemism is high in some groups, for example 81% of mammals (Mammalia) are endemical. Class Mammalia is divided on two subclasses: subclass Prototheria is a primitive group of egg-laying mammals, and subclass Theria includes two interclasses: Metatheria and Eutheria. Metatheria (marsupials) are viviparous but they are producing youngs who are on very low level of development. Mother's pouch gives them entirely protection until they became independent. Marsupials have evolved by occupying special ecological niches and in many cases they are morphologically related to placental mammals in Eurasia and Americs who require similar niches – phenomenon of convergent evolution. Metatheria includes seven orders, three are in Americs and four are in Australia and Oceania: Diprotodontia, Dasyuromorphia, Peramelemorphia and Notoryctemorphia. Australia is the world of Metatheria and on other continents they have been repulsed by interclass Eutheria (placental mammals). The biggest threat to Metatheria in Australia represents the introduction of non-native Eutheria who usually win in competition for food and space. Native orders of terrestrial Eutheria in Australia are the representatives of Rodentia, Chiroptera and Carnivora. In this work is a review of families and particular species of Prototheria and Eutheria who represent Australian paleoendemics, and families and particular species of Eutheria who represent Australian neoendemics.