One hundred patients who were injured by London underground trains during 1981-6 were studied; 43 of them died. Deliberate self harm was probable in roughly three quarters. Alcohol intoxication was thought to play an important part in a further tenth of cases. Thirteen were psychiatric inpatients at the time of the incident, and a further two had recently been discharged. Early warning of a potential suicide attempt was given during the 24 hours preceding the incident in 15 of the cases. Some of the deaths in the psychiatric patients may have been preventable.