Children with blindness due to retinopathy of prematurity (ROP)--who are at greatly increased risk of cerebral damage--have been noted to have a high rate of autistic symptoms, but systematic controlled studies have been lacking. A controlled population-based study was performed; one group was blind due to ROP (N=27) and the other was congenitally blind due to hereditary retinal disease (N=14). Fifteen of the 27 children with ROP had autistic disorder. All these children were mentally retarded and about one-third of them had cerebral palsy. In the comparison group, two of the 14 children had autistic disorder. It is concluded that there is a strong association between ROP and autistic disorder. The association is most probably mediated by brain damage and is largely independent of the blindness per se.