BACKGROUND: Increased attention is given to aggression and violence in people with mental disorders, though little is known of what aspects of mental disorders are associated with violence or about the strength of these associations. MATERIAL AND METHODS: A review of the topic is given based on international research. RESULTS AND INTERPRETATION: Many studies have reported an increased risk of homicide among people suffering from schizophrenia. There are many ways of classifying symptoms in schizophrenia and there has been a clinical impression that violence is related to positive symptoms and disorganization. However, the predictive value of symptoms is small compared to such characteristics as early onset of antisocial behaviour, antisocial and psychopathic traits, earlier violence and abuse problems. Alcohol and substance abuse is associated with an increased risk of violent behaviour in people with and without mental disorders. Recent research suggests that this increased risk is larger still in people with schizophrenia than in people with no mental disorders.