Atypical antipsychotics are increasingly used in the treatment of severe behavioral disturbances in people with pervasive developmental disorders. Among these compounds, risperidone has been the most broadly studied. This drug profile will review the available data on the use of risperidone in individuals with pervasive developmental disorders. In addition, the chemistry, pharmacokinetics, pharmacodynamics and metabolism of risperidone are discussed. Emphasis will be placed on adverse effects associated with risperidone in these people, including a discussion of measures that can be taken to monitor for these effects. Finally, a discussion of the future direction of risperidone use in this population and key issues will be presented.