Purpose of review The literature has often suggested that individuals with intellectual disability who have an autism spectrum disorder (ASD) experience higher rates of mental health problems than those without ASD. This finding has been challenged in recent years and so the purpose of this article was to critically review relevant studies since March 2009. The review focuses on studies specifically about the mental health of adults with intellectual disability who have ASD. Recent findings Recent studies do not support the hypothesis that adults with intellectual disability and ASD are more vulnerable to psychiatric disorders than those without ASD. Factors found to be associated with poorer mental health include severity of intellectual disability, adaptive behaviour skills and social skills. Summary The evidence base on the mental health of adults with intellectual disability and ASD is small but rapidly increasing. Studies tend to have relatively small sample sizes and there remain difficulties in accurately assessing ASD and psychopathology in adults with intellectual disability.