This paper is concerned with a group of cases presenting certain psychiatric symptoms following exposure to the detonation of a nearby high-explosive bomb. These cases show features and present problems which appear from the current literature in this country to have received insufficient attention, or none at all. The cases to be presented are not all of equal significance, but in each there are certain common features which, from the psychiatric angle, have a definite and unmistakable organic stamp, and indicate a relationship, direct or indirect, of the syndromes to structural changes in the brain. These symptoms are characteristic in fact of a slight or moderate degree of cerebral trauma. This relationship is prone to be too easily overlooked. The reasons for this are :

(1) The absence in many cases of a definite history of head injury.

(2) The absence as a rule of at least a long period of unconsciousness.

In consequence, when the patient is seen perhaps some considerable time later this possibility is not considered, and the reaction is dismissed as psychogenic. That this can be done even by trained observers was demonstrated in three of the cases about to be described. All the patients except one were Naval personnel who were exposed to blast in air-raids either ashore or at sea.