Thirteen patients with acute subdural and epidural hematomas were found to have fresh, unclotted blood at the time of surgical decompression several hours after injury. Computed tomographic (CT) scans of these patients demonstrated areas of hyperdensity, corresponding to clotted hematoma, admixed with areas of isodensity, corresponding to liquid blood. Active bleeding from identifiable loci was found in 11 patients, 4 of whom had massive hemorrhages. Clotting abnormalities ranging from slightly elevated laboratory test results to a full-blown clinical picture of disseminated intravascular coagulation occurred in 8 patients. We describe the CT pictures of these "hyperacute" lesions, and we postulate that such CT presentations indicate either the presence of ongoing active intracranial bleeding or the onset of a coagulopathy complicating the management of these lesions.