Complex regional pain syndrome (CRPS) is a controversial, ambiguous, unreliable, and unvalidated concept that, for these very reasons, has been justifiably ignored in the “AMA Guides Library” that includes the AMAGuides to the Evaluation of Permanent Impairment (AMA Guides), the AMA Guides Newsletter, and other publications in this suite. But because of the surge of CRPS-related medicolegal claims and the mission of the AMA Guides to assist those who adjudicate such claims, a discussion of CRPS is warranted, especially because of what some believe to be confusing recommendations regarding causation. In 1994, the International Association for the Study of Pain (IASP) introduced a newly invented concept, CRPS, to replace the concepts of reflex sympathetic dystrophy (replaced by CRPS I) and causalgia (replaced by CRPS II). An article in the November/December 1997 issue of The Guides Newsletter introduced CRPS and presciently recommended that evaluators avoid the IASP protocol in favor of extensive differential diagnosis based on objective findings. A series of articles in The Guides Newsletter in 2006 extensively discussed the shortcomings of CRPS. The AMA Guides, Sixth Edition, notes that the inherent lack of injury-relatedness for the nonvalidated concept of CRPS creates a dilemma for impairment evaluators. Focusing on impairment evaluation and not on injury-relatedness would greatly simplify use of the AMA Guides.