In a population study of altogether 1,112: 60-, 50-, and 30-year-old men performed in G?teborg, Sweden, data on head injuries suffered during life were obtained by personal interview. Two head injury concepts were used, one wide definition to cover all sorts of head injuries (HI-w) and one restricted only to delineate head injuries with evidence of presumed brain involvement (HI-r). 24% of the 60-year-old men, 21% of the 50-year-old men and 23% of the 30-year-old men reported at least one head injury with unconsciousness. When taking only the 3 first decades of life into account a significantly higher proportion of men in the youngest cohort had been unconscious than in the older ones, and the youngest men also had a significantly higher incidence of both HI-w and HI-r than the older men. Accidents at home, in roads and in sports/recreational areas dominated in childhood, place of work in adult age. HI-r accidents occurred somewhat more often in roads and sports/recreational areas than HI-w accidents. Falls, traffic and blows/impacts were the most common causes. Falls dominated in childhood. Motor vehicles were more often involved in childhood accidents in the youngest cohort than in the two older ones. The proportion of self-care decreased due to a strong secular trend. Out-patient care increased due to both a secular trend and to the age of the victim. The proportion of in-patient care increased with the age of the victim but showed no evident secular trend. 1/5 to 1/3 of all head injuries with unconsciousness were not medically attended.