Clinical Impairment Assessment is done according to the American Medical Association Guides to the evaluation of permanent clinical impairment. We normally use the revised 5th edition of the American Medical Association Guides. Recently, 6th edition of the American Medical Association Guides has been published and in the near future, we will start using the 6th edition for assessment of clinical impairment and disability. In Ontario, we use the 4th edition of the American Medical Association Guides for assessment of clinical impairment and disability and for evaluation of catastrophic injuries, as well as assessment of chronic pain.