The authors report 8 patients who developed an epidural hematoma after having been submitted to 1 or 2 computed tomographies (CT) which did not yet show the hematoma. The initial CT was done 1 to 6 hours after the accident. The delayed hematoma was diagnosed 3 and a half hours to 7 days after the accident. Secondary clinical deterioration occurred in 6 patients and was dramatic in 4 of them. Delayed epidural hematoma seems to be a frequent event; our 8 cases represent 10 % of all epidural hematomas operated during the period under consideration. This has to be taken into account when taking care of head injured patients after negative CT. The authors propose a list of indications for repeating CT. The current views on mechanisms of formation of epidural hematomas are discussed in the light of the increasing number of reported cases of delayed epidural hematoma.