In 1939 an inquiry was begun into the late results of the type of head injury which results from collisions on the roads, from accidents in industry and from falls in the home. Since penetrating injuries resulting from civilian accidents are extremely rare, the examples that were encountered have been eliminated from the final reckonings and so the following account is concerned entirely with the so-called closed type of injury. It must, of course, be realized that compounding and infection are common even in this type of injury, because cranial fractures frequently run across and open into the paranasal air sinuses.