Post-traumatic acute epidural hematoma (EDH) is generally visible on the CT scan done immediately after admission: occasionally, it only comes to light at a later scan and is then termed delayed (DEDH). Since the introduction of CT, the frequency of this occurrence has gone up from 6-13% to 30%. The mechanisms responsible for the delayed appearance of the epidural hematoma a "tamponade" effect are usually increased endocranial pressure and post-traumatic arterial hypotension as well as, in a limited number of cases, coagulopathy, CSF drainage, and arterio-venous shunt. The authors report 5 of their own cases and 45 published cases and discuss the characteristics of this particular form of hematoma and its outcome.