The study consisted of a prospective investigation of 45 consecutively admitted patients who had sustained a mild head injury. In all cases the duration of post-traumatic amnesia was less than 24 hours. Head injury patients had an average of three adverse life events in the year preceding injury compared with 1.5 for controls. Using the PSE, 39% of the group were diagnosed psychiatric cases at six weeks after the injury. For cases the mean level of chronic social difficulties (3.3) was four times that for non-cases (0.8). Six months after injury, 28% of the head injury group had three or more symptoms. These chronic cases were on average ten years older than those whose symptoms had remitted. Chronic cases had, on average, three social difficulties, twice as many as found among those whose symptoms had remitted. The emergence and persistence of the postconcussional syndrome are associated with social adversity before the accident. While young men are most at risk of minor head injury, older women are most at risk of chronic sequelae.