We studied 128 patients admitted over a 12 1/2-year period to the Cook County Hospital Trauma Unit with acute subdural hematoma (ASDH): 82 were admitted directly and 46 were admitted after transfer from another hospital; 59% of the entire group died and only 27% obtained a functional recovery. As a group, the transferred patients, who suffered delays of several hours before receiving definitive surgical care, fared significantly worse than the patients with equivalent trauma who were admitted directly. The mortality of the transferred patients was 76%, compared to 50% of the direct admit patients. The outcome was also worse for transfer patients who experienced a 'lucid interval' or with alcohol intoxication. We conclude that the delays associated with failure to admit patients with ASDH directly to a head trauma center cause an excessive mortality and morbidity which could potentially be avoided by proper triage.