Violent behaviours such as aggression or self-harming are commonly observed in persons with autistic disorders. They constitute the main reason for emergency admissions of these patients to the hospital and can sometimes result in substantial physical injuries toward the patients themselves or towards others. Atypical antipsychotics have been emerging for some years as the first-line pharmacologic treatment for violence in children with autism or other pervasive development disorders. in particular, the anti aggressive effect of risperidone and olanzapine has been found significant in double-blind, placebo-controlled trials and North American and European agencies recently approved the use of risperidone for the treatment of aggressiveness in children with autism. by contrast, clozapine has received very little attention so far.

Here we report the case of a 15-years old adolescent with autism whose severe tantrums and violent behaviours were not improved by risperidone or haloperidol but were drastically improved with clozapine (more than 40% reduction of violent events). the anti aggressive effect of clozapine has been sustained for one year of follow-up. No significant side effects were reported in this patient and co prescription was reduced by 50%. This case report suggests the importance to conduct controlled trials assessing the efficiency of clozapine for the treatment of aggressiveness in patients with autism. More generally, specific anti aggressive properties of clozapine are discussed in the light of the relevant literature.