We have examined the epidemiological background of 134 consecutive patients admitted to our centre who suffered from post-traumatic unconsciousness of over 1 month's duration. The incidence of such unconsciousness in Israel is estimated as 4 per 1,000,000, or one case in 410 hospitalizations for head trauma. The cause of trauma was a road accident in 69% of cases. Among victims, pedestrians and cyclists were more likely than four-wheeled vehicle drivers and their passengers to suffer from prolonged unconsciousness, from which they were less likely to recover.