Background: We examined the benefits of risperidone, including quality of life (QoL), in the treatment of violent and self-injurious behaviour in adults with moderate, severe or profound intellectual disability. Methods: Twenty-four participants received open-label, oral, flexible-dose risperidone of 0.5-6 mg/day for 12 weeks. Efficacy was measured primarily using the Aberrant Behaviour Checklist (ABC) and secondarily using validated measures of depression, autism, QoL and global condition. Safety and tolerability were also assessed. Results: Total ABC significantly improved from baseline by week 1. This improvement was maintained throughout the study (final visit, P less than 0.001). Secondary efficacy measures were also improved with risperidone, including QoL measures (final visit: home life, P less than 0.001; activity, P = 0.002; skills, P = 0.014). Risperidone was generally well tolerated, with no unexpected adverse events. Conclusions: In this open-label trial, risperidone was efficacious and well tolerated for managing violent and self-injurious behaviour and improving QoL in adults with moderate, severe or profound intellectual disability.