Homeless service users were screened for autism spectrum disorder through one of Ireland's leading not for profit service providers. Keyworkers acted as proxy informants; their caseloads were screened using the DSM-5--Autistic Traits in the Homeless Interview (DATHI). Client current and historical health and behaviour data was collated. A representative sample of 106 eligible keyworkers caseloads were screened, identifying 3% "present" and 9% "possibly present" for autistic traits with the DATHI. These findings suggest a high estimate of autism prevalence and support emerging evidence that, people with autism are overrepresented in the homeless population, compared to housed populations. Autism may be a risk factor for entry into homelessness and a challenge to exiting homeless and engaging with relevant services.