Considerable number of intellectual disabled people experience some form of disruptive behavior. Antipsychotics are the most common treatment for these behaviors. Numerous patients were efficiently treated with thioridazine, recently withdrawn. The authors describe a case series of "thioridazine responders" treated with olanzapine. Thirty three patients with severe intellectual disability were recruited. All patients were assessed for seven types of disruptive behavior on five point scale. Patients with severe behavior disturbances were included in treatment. The time points of assessment were at day 0, 30, 60 and 180. Twenty one patient accomplished inclusion criteria. A significant decrease occurred at day 30 for all types of behavior. Total score, self injurious behavior, compulsive and destructive behavior showed further decrease at day 60 and became stable until the end of study. Olanzapine appears to be efficacious in the treatment of disruptive behavior in the intellectually disabled and could be substitute for thioridazine treatment.