Suicide and self-harm are important health problems worldwide and an important cause of premature mortality. Advances in epidemiology, neuroimaging and genetics may help to improve our understanding of these complex behaviours. Men are more likely to use violent methods such as hanging or shooting, whereas women are more likely to poison themselves with antidepressants or analgesics. Rates of suicide vary widely between countries. The suicide rate varies according to social class, with the highest rate being found in the lowest classes and the lowest rate in the professional classes. The association of mental disorder with suicide is consistent across settings. Two main methodological approaches have been used to explore this relationship: the psychological autopsy study and the follow-up study. A number of psychological characteristics are more common among those who self-harm; these include impulsivity, poor problem solving and hopelessness.