Autism is now thought to be present right from birth. Although usually not officially diagnosed until after the child's second birthday, parents often report disturbances before then. The age of detection of disturbances varies and may be linked to differences in the severity of the autism and its associated retardation. This study evaluates the developmental characteristics of 193 children with pervasive developmental disorder, using the same standard procedures for all subjects. Our goal was to determine the relationship between age of parental recognition of disturbances and disorder severity. The results indicated mainly a link between early abnormalities, associated medical condition and severity measured on cognitive tests. They suggest systematic screening for signs of autism in very young children.