Alcoholic intoxication and a traumatic intracranial lesion have many features in common. It is important for a doctor not to make an incorrect diagnosis between these two conditions, but it is difficult in some cases. The effect of alcohol on the conscious level may complicate the assessment of patients and make it more difficult to recognize the development of complications such as intracranial hematoma. The most immediate and correct diagnosis can be obtained by estimating the amount of alcohol in a patient's blood although it is often difficult in the usual emergency departments in Japan. To try to throw some light on this question, we decided to attempt both clinical and laboratory diagnosis of alcohol ingestion. In 68 adult patients who had head injuries with conscious disturbance admitted to our ward at night, alcohol levels in their blood were estimated by gas chromatography, during the past 24 months. At the same time clinical examinations for the diagnosis of drunkenness were made: on admission, it was recorded whether all patients had white or red conjunctiva, whether speech was clear or slurred, whether there was a distinctive smell on their breath, and whether coordination was good or poor. Of 68 patients (63 male, 5 female), 7 had no alcohol in their blood and 61 had positive alcohol results. The mean blood alcohol level was 233 +/- 130 mg/dl. Clinical diagnosis of alcohol ingestion; The amount of alcohol in the blood correlated highly with the strength of the smell on their breath and of conjunctival injection (p less than 0.001), on the other hand, did not correlate with the speech disturbance, skillfullness of coordination and level of consciousness.(ABSTRACT TRUNCATED AT 250 WORDS)