Sir: The pharmacotherapy of autism and pervasive developmental disorders primarily targets central serotonin or dopamine pathways. The use of haloperidol in treating autism in children was well studied in several double-blind, placebocontrolled studies by Campbell and associates. In addition, a double-blind, placebo-controlled study by McDougle et al. showed that the selective serotonin reuptake inhibitor (SSRI) fluvoxamine reduced repetitive thoughts and behavior, maladaptive behavior, and aggression in adults with autistic disorder.