Practice regarding the use of thiamine in head-injured patients at risk of Wernicke-Korsakoff syndrome in Scottish neurosurgical units was surveyed by questionnaire and revealed no clear policy. A 2 year retrospective study of 218 admissions to one of these units of patients who had taken alcohol shortly before sustaining head injury is also described. The minority (20.6%) of the total had been given thiamine, with just over half (56.1%) of those categorized as alcoholic receiving this treatment. Additional carbohydrate loads, in the form of i.v. dextrose or parenteral nutrition, had been given to 44.5% of patients and only 28.9% of this group had also been given thiamine. The dose and duration of thiamine given was inadequate in most cases. It is suggested that failure to ensure that head injury patients at risk of Wernicke-Korsakoff syndrome receive appropriate thiamine prophylaxis represents a missed and treatable additional insult to the damaged brain.