A survey conducted in four French regions identified a sample of 154 autistic children born in the birth cohorts 1972 and 1976. Their mean ages were respectively 6.9 and 5.5 years when their handicaps were registered to local administrative services. The overall prevalence estimate is 4.9/10,000, with little difference between the two cohorts. The boy/girl sex ratio is 2.1:1, and more than two thirds are mentally retarded. The SES distribution does not deviate from census data. An elevated incidence of epilepsy is found (22%), with higher rates among the most retarded subjects and those with perinatal antecedents. Otherwise, relatively few autistic subjects were reported to have a clearcut medical disorder known for its association with autism.