The behavioral characteristics of five preschool boys with Leber's congenital amaurosis were compared with those of five preschool boys who had been blind from birth from other causes. The boys with Leber's amaurosis met criteria for infantile autism and had remarkably similar developmental histories. They had significantly higher ratings on the Childhood Autism Rating Scale for both frequency and severity of autistic symptoms. The two groups also had different profiles on the Autism Behavior Checklist, the Leber group having a distinctive profile and higher scores. It is suggested that cases of Leber's amaurosis may account for some descriptions in the literature of the co-occurrence of autistic behavior and blindness in children. Deficits in cerebellar structure have been reported in some Leber patients and in some autistic children, which may provide the neurological basis for the behavioral similarities seen in children with Leber's amaurosis and sighted autistic children.