Breath alcohol analysis was undertaken in 1044 consecutive patients aged over 15 years attending the Accident and Emergency (A and E) Department of a rural district general hospital during a 50-day period. 16.5 per cent of all patients had the smell of alcohol on their breath, with 10.2 per cent of the patients recording a breath alcohol level equivalent to a blood level of 80 mg/100 ml or more. One-third of all patients attending between 9 pm and midnight, and almost two-thirds of patients attending between midnight and 3 am had positive breath tests. Positive breath tests were most likely in males, patients with head injuries, with overdoses, in victims of assault and in patients with a depressed conscious level, irrespective of cause. Clinical estimation of intoxication by alcohol may be accurate in the co-operative patient, but in the patient with a head injury or with a depressed conscious level from another cause, this is more difficult. Breath alcohol analysis is rapid, not-invasive, accurate and of clinical value in these and other high-risk patients attending hospital as emergencies.