Six observations of post-traumatic acute respiratory insufficiency of alveolar origin are reported briefly. Three of them have been attributed to a Mendelson's syndrome. This authors showed that diagnosing these lung diseases by acid inhalation is particularly difficult in casualties. It is a diagnosis by elimination which no certainty can prop. These post-traumatic Mendelson's syndrome are serious and difficult to prevent. In the three cases reported two accidents occurred during or immediately after an intubation. The systematic use of an efficient anti-acid could be recommended in all serious casualities.