Dynamic X-ray follow-ups were conducted after pneumo-encephalography (PEG) of 28 patients who had suffered a severe craniocerebral trauma (intracranial hematoma, crushing of the brain), and those suffering from a post-traumatic disease of the brain. PEG was carried out in periods from 3 months to 3 years after the trauma had occurred. X-ray control was established immediately after the endolumbar infusion of air into the intracranial cerebrospinal fluid spaces, and subsequently every 24 hours till the complete disappearance of air from the ventricles of the brain. Investigation showed that in most cases a more reliable picture of the size of the ventricles can be obtained not on the day that PEG is performed, but in remoter periods (24--48 hours). The internal hydrocephaly that occurs in most patients is evidently of aresorptive character. The expansion of subarachnoidal spaces, rather than their obliteration, is more characteristic of a traumatic disease of the brain, including post-traumatic epilepsy. These changes, however, are not pathognomonic for a complicated severe craniocerebral trauma.