BackgroundAutistic spectrum disorder encompasses a wide variety of behavioural and communicative problems. Both the core features and noncore features of autism have been targeted in a variety of therapies. Atypical antipsychotic medications, including risperidone, have been used for symptom and behaviour improvement and have shown beneficial outcomes, particularly in certain aspects of the disorder. However, given the nature of the condition presenting in young patients, the risks of these potentially long term therapies must be weighed against the benefits. ObjectivesTo determine the efficacy and safety of risperidone for people with autism spectrum disorder.