Purpose <p>The aim of the present study was to determine whether autistic individuals self-report their autistic symptomology similar to how a significant other and clinician does. Of further interest was investigating whether requiring autistic individuals to self-report on assessment tools which require them to hold insight as to how their behaviours are perceived by others contributed to low concordance between self-reports and reports provided by significant others.</p> Methods <p>Archival diagnostic data of 62 autistic adults were extracted from a private psychology practice’s online database. These data included SRS-2 self and informant raw item scores, and standardised and raw subscale scores. Adaptive functioning data, and demographic variables including age and gender of the autistic person were extracted. Further, a clinician’s impression of the self-reporter’s autistic characteristics was measured via the Autism Behaviour Inventory – Clinician Version.</p> Results <p>We found low concordance between self and informant SRS-2 reports on all SRS-2 subscales, including items requiring insight. This low concordance was driven by females who tended to report lower SRS-2 scores relative to their informant. Limited evidence was found in support of a relationship between SRS-2 self and informant-reports when compared to a clinician’s impression.</p> Conclusion <p>Although tools such as the SRS-2 are used by clinicians to gather information during autism diagnoses, self-reports and informant reports in this study were not always concordant. Further they did not map well with clinician’s impressions. Perceptions of difficulty vary between persons doing the reporting, highlighting the need for a multi-faceted and multi-informant approaches to diagnostic assessments.</p>