In the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides), Fifth Edition, the methods for rating impairment to causalgia, reflex sympathetic dystrophy (RSD), and complex regional pain syndromes (CRPS) differ from the approaches found in previous editions. Methods for evaluating impairment due to causalgia, RSD, and CRPS can be described as having anatomic or functional bases. The physical evaluation determines the anatomic impairment and is based on history and a detailed examination; the functional evaluation measures the individual's performance of the activities of daily living (ADL). Chapter 13 of the AMA Guides, Fifth Edition, considers causalgia and RSD in Section 13.8, Criteria for Rating Impairments Related to Chronic Pain, and defines chronic pain as the diagnoses of causalgia, posttraumatic neuralgia, and reflex sympathetic dystrophy. In contradistinction to Chapters 16 and 17 and the Glossary, the new term CRPS is not used here. Chapter 16 considers CRPS, RSD (now CRPS I), and causalgia (now CRPS II) and notes that, “contrary to previous suggestions, regional sympathetic blockade has no role in the diagnosis of CRPS.” Chapter 17 uses a functional approach for assessing impairment due to causalgia, RSD, and CRPS. Pending further guidance, evaluators should ensure that their methods for rating lower extremity impairments due to causalgia, RSE, and CRPS are internally consistent.