Resumo. This work aimed to evaluate the natural durability of heartwood and sapwood of Luhea divaricata, Carya illinoinensis and Platanus x acerifolia. Test samples measuring 2.5 x 2.5 x 30.0 cm (radial x tangential x longitudinal) were placed in a pine forest stand and an open field. During a year, the samples were repeatedly weighed and evaluated by a rating system to determine mass loss and decay index, respectively. The results showed that regardless of species and type of wood, the forest environment is more favourable to decay than that of the open field. Despite the high correlation between mass loss and decay index, variations in the durability of wood were found between these parameters. The wood from the internal section of the log (sapwood) was the more affected. For mass loss, no significant variation was observed for the species analyzed, however, for the decay index Platanus x acerifolia was shown to be the most affected.