The natural durability of two Eucalyptus species (E. bosistoana and E. sideroxylon) planted in Uruguay was compared with that of E. tereticornis. Twenty-year-old tree specimens used in this study had originally been planted for trials of Eucalyptus species able to grow on soils developed on basalt. Populus sp. and Pinus taeda were used as references in this preliminary test. The durability of these species was evaluated against one white rot fungus (Coriolus versicolor) and one brown rot fungus (Gloeophyllum trabeum). The two Eucalyptus species were classified as not durable, while E. tereticornis can be considered resistant.