Eleven new species of Amanita, Amanitaceae, are described from the southern Eucalyptus-dominated forests of Western Australia. One distinctive species is referred to subgenus Amanita, section Amanita. The other 10 species are members of the subgenus Lepidella, 5 in section Lepidella, 2 in section Validae, and 3 in section Phalloidae. All 11 species were fruiting in native Eucalyptus forests from 247 km north of Perth to Albany, 424 km south of Perth, on the southern coast. Key words: Basidiomycetes, Amanitaceae, Amanita, Eucalyptus, Western Australia.