In this study the post-traumatic syndrome was investigated. It was found difficult to define the limits of this condition, and particularly to distinguish it from post-traumatic hysteria. Therefore, both diagnoses were temporarily ignored, and the injury was broadened to the general sequelae of head injuries, other than definite defects caused by known neurologic lesions.These sequelae are psychosomatic in the truest sense of the term. They represent an intricate combination of organic and emotional processes. It seems that the symptoms following head injuries signify the sum of two quantities: 1. The damage to the brain and its surrounding structures; and 2. The patient's emotional reaction to this damage and to the experience of the trauma.The important problem is to assess the proportion of each quantity in individual cases. In the hope of contributing to its solution, psychiatric follow-up of head injured patients has been instituted.