Introduction: Mental health assessment in autistic individuals with intellectual disabilities may be challenging. Findings from non-autistic samples indicate overlap between obsessive-compulsive disorder (OCD) and psychotic disorder/schizophrenia, but little is known about this potential overlap in autistic people. Methods: Explorative, retrospective chart study involving comprehensive, multimodal assessments for 18 autistic individuals with suspected OCD in a specialized mental health department. All participants had an intellectual disability (12) or significant impairments in adaptive behavior (6). Results: While no participants had been diagnosed with psychotic disorder at referral, 7/18 participants were diagnosed with a psychotic disorder following assessment (schizophrenia or unspecified psychotic disorder). Conclusion: OCD symptoms may overshadow psychotic symptoms in autistic individuals with intellectual disabilities. A combination of conventional assessment tools and assessment tools developed for autistic people may be helpful in differentiating OCD and psychosis in this population, as well as prototypical symptom considerations and exploring the developmental trajectories of symptoms.