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A National Guideline for the Assessment and Diagnosis of Autism Spectrum Disorders

The National Guideline for the Assessment and Diagnosis of Autism Spectrum Disorders is the first, unified approach to the assessment and diagnosis of autism in Australia.

The Guideline provides health professionals with a nationally consistent, step-by-step process to follow. This process spans from the time of referral until assessment results are shared with individuals and caregivers, including suggestions to meet support needs.

For parents and caregivers of children undergoing an assessment, and adults, the Guideline will help you to understand this process and ensure you are receiving appropriate clinical care.

What does the Guideline mean for me?

Access a video and fact sheet that explain the Guideline and what to expect from an assessment.

Frequently Asked Questions

The National Guideline for the Assessment and Diagnosis of Autism Spectrum Disorders was launched in October 2018.

The Guideline defines a clear, step-by-step process for the assessment and diagnosis of autism spectrum disorders. This process will help health professionals determine an individual’s support needs, and whether they meet the criteria for a diagnosis.

One of the main aims of the Guideline was to agree a consistent, national approach to remove confusion and uncertainty for those undergoing an assessment.

The Guideline does not redefine or change the specific criteria for a diagnosis of autism – as outlined in the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) and the International Statistical Classification of Diseases and Related Health Problems (ICD-11).

Autism spectrum disorder (ASD) is a neurodevelopmental condition. Individuals on the autism spectrum may show difficulties with social and communication skills, and display a variety of behaviours and intense or focused interests. The signs and behaviours that characterise autism are often present before three years of age, but may first become apparent during the school years or later in life. Autism can vary widely in nature and impact, and may be accompanied by mental and physical health problems.

There is no biological test – such as a blood test or brain scan – for autism. It is usually diagnosed by trained health professionals, who observe certain characteristics such as social communication, behaviours and intense or focused interests.

The Guideline defines a clear process for the assessment and diagnosis of autism that aims to reduce stress, confusion and delays in service provision.

Primary healthcare providers (such as GPs, nurses, allied health professionals or Aboriginal health workers) are usually the first point of contact. They can begin the process by referring you to a health professional who has experience in assessing neurodevelopmental conditions.

After referral to an expert health professional, the Guideline recommends a Comprehensive Needs Assessment is carried out, followed by a Diagnostic Evaluation.

The Comprehensive Needs Assessment will look at an individual’s strengths and level of functioning in different areas, any support needs they may have, and whether there could be a medical explanation for the behaviours or characteristics that have prompted the referral.

If required, a Diagnostic Evaluation will then take place to establish whether behaviours are consistent with autism and/or another diagnosis.

The number of sessions and the health professionals involved may differ according to a range of factors. These factors may include the complexity of the behaviours or characteristics of the individual, their geographical location and the organisation where the assessment is conducted.

The purpose of the Comprehensive Needs Assessment is to understand the strengths, challenges and needs of the individual being assessed. This assessment consists of two parts: an Assessment of Functioning and a Medical Evaluation.

Assessment of Functioning

This assessment is carried out to obtain a detailed understanding of an individual’s level of ability and support needs across a broad range of areas. These areas include cognitive abilities, speech and language function, daily living skills, relationships, school or work. Some of the information collected during this assessment will be about the individual’s:

  • medical and health history
  • family history
  • developmental and functional abilities.

An Assessment of Functioning may be performed by one or more medical and/or allied health professional. This could be a medical practitioner (e.g. GP, paediatrician, psychiatrist), nurse practitioner, occupational therapist, psychologist, social worker or speech pathologist with relevant training and expertise.

Medical Evaluation

The Medical Evaluation is about understanding if there are medical causes for the behaviours or characteristics that have prompted the referral. A Medical Evaluation involves a physical examination and other specific medical tests.

Medical Evaluation is completed by a medical practitioner, such as a paediatrician, psychiatrist or GP.

If the findings from the Comprehensive Needs Assessment support the possibility that autism may be a diagnosis, the Guideline recommends a Diagnostic Evaluation to establish whether behaviours are consistent with a diagnosis of autism or another condition. This may involve a review of collected information, interviews with the individual and other key people in their life, and professional observation and assessment of characteristics and behaviours.

One health professional with specific expertise may conduct the Diagnostic Evaluation, or they may invite a team of health professionals to make a consensus diagnostic decision together. The professionals who are involved will depend on a range of factors, such as the type or complexity of characteristics, and any other conditions the individual may have.

After the assessment, the Guideline recommends that the health professionals involved provide the individual and/or their caregivers with a written report. The Guideline also recommends that a health professional explains the content of the report in a meeting.

The report will summarise the information collected during the assessment and what this information means. It will also explain any decisions that have been made about a diagnosis, and suggest next steps for accessing support services.

The Guideline recommends a nationally consistent, best-practice process for the assessment and diagnosis of autism. This will help health professionals deliver the best possible care. The process also aims to reduce the individual’s and their caregiver’s stress and confusion and lessen any delays while seeking services.

Reading the Guideline and supporting resources will help you understand the assessment process and help ensure that you receive appropriate clinical care.

The Guideline does not change the status of existing diagnoses. You do not need to have another diagnostic assessment. The Guideline describes a recommended process for current and future clinical practice.

The Guideline describes a recommended process for the assessment and diagnosis of autism. If you have queries about the diagnostic process you went through, or the publication of the Guideline, you should discuss this with the clinician/team that conducted your diagnostic assessment, or seek a second opinion. If the clinician/team that conducted the previous diagnostic assessment has suggested you/your child is reassessed in the future, it should follow the process described in the Guideline.

No. The Guideline has been developed specifically for Australia, and incorporates sufficient flexibility to ensure that recommendations can be adapted to the wide variety of contexts across the country.

For more information, please contact Autism CRC on 07 3377 0600 or email

NHMRC approval of Guideline recommendations

The recommendations on pages 3-60 of the Guideline document were approved by the Chief Executive Officer of the National Health and Medical Research Council (NHMRC) on 9 July 2018, under Section 14A of the National Health and Medical Research Council Act 1992. In approving the Guideline recommendations, NHMRC considers that they meet the NHMRC standard for clinical practice guidelines. The approval is valid for a period of 5 years. NHMRC is satisfied that the Guideline recommendations are systematically derived, based on the identification and synthesis of the best available scientific evidence, and developed for health professionals practising in an Australian health care setting. The Guideline reflects the views of the authors and not necessarily the views of the Australian Government.