To better record and characterize mortality in the declining population of dugong (Dugong dugon) in southeast Queensland, Australia, animals were collected and brought to the University of Queensland for postmortem examination. Fifty-five animals were examined over a 14-yr period. Human activities commonly caused the animal death. Several deaths were attributed to primary or secondary infections and idiopathic and degenerative diseases. A significant proportion of animals were found to have nonspecific signs of chronic debility, but the causes of disease and mortality in these cases remains to be identified.