The aim was to characterize the panorama of developmental disorders in 208 preschool children with a clinical diagnosis of autism spectrum disorder (ASD), referred to a specialized centre, the Autism Centre for Young Children (ACYC), for intervention. At the centre, a research team examined all children according to structured protocols and interviews. All available test data from their assessments prior to referral were scrutinized. The boy:girl ratio was 5.5:1. In 22% of the total group a period of regression, including speech and language, had occurred. Epilepsy had been diagnosed in 6% of the children. In 38% of the children there was a definite or highly suspected learning disability/mental retardation according to cognitive test results. About the same proportion had a developmental delay that at the time of assessment could not be definitely classified and in 23% there were clear indications of a normal intellectual function. About 40% of the group exhibited hyperactivity. Differences in expressive vocabulary and adaptive functioning were strongly related to cognitive level. About 20% of the group had AD as the dominating developmental disorder, i.e., they represented a clinical picture of ''classic'' autism. The majority in this group also had learning disability. Another 20%, had ASD combined with a normal intellectual level, some of these conformed to the clinical picture of Asperger syndrome. In a relatively large group (more than half) learning disability or a general developmental delay was as evident as the ASD. In a smaller group (8%) ASD criteria were questionably met. In this group attention deficits in connection with speech and language problems were prominent. The highly individual developmental profiles seen in children with ASDs have to be taken into account when planning intervention and follow-up. The children's medical characteristics also vary considerably and will be detailed in a further report. (Contains 4 tables and 1 figure.)