BackgroundAlthough many adults with learning disabilities show features of autistic syndrome, there have been very few population-based studies. We explored the prevalence of autistic traits and their association with maladaptive behaviours in a geographically defined population of adults with learning disabilities.MethodThe carers of 220l adults with learning disabilities were interviewed, and information was sought concerning aspects of their behaviour and ability. Individuals were scored according to the number of core autistic traits displayed. The prevalence of autistic traits was examined in respect of aspects of behaviour and ability.ResultsAutistic traits were common among adults with learning disabilities. Those with a higher number of autistic traits were more likely to be profoundly learning disabled and demonstrate awide range of challenging behaviours.ConclusionsMany adults with learning disabilities demonstrate autistic traits. The relationship of autistic traits with challenging behaviour has major implications in service planning and delivery.