Six cases of acute respiratory insufficiency are presented. Particular reference is made to the pathogenetic mechanisms of the syndrome and the term ARDS is examined. The definition "acute respiratory insufficiency due to post-aggressive pulmonary dysmetabolism" is proposed. An account is also given of satisfactory results obtained by interdepartmental along-to-date lines. It is hoped that knowledge of this often fatal syndrome will not be confined to resuscitation services, but extended to other hospital departments.