Although there have been many studies of violent behaviour, anger has been neglected as a subject of scientific and clinical investigation. Anger can be defined as an affective state experienced as the motivation to act in ways that warn, intimidate or attack those who are perceived as challenging or threatening. Anger is associated with sensitivity to the perception of challenges or heightened awareness of threats. Anger is likely to be closely associated with fear. Although anger is common in mental illnesses it is largely neglected, perhaps because of the social stigma attached to its expression.