Many states require use of the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides) in their workers’ compensation systems; state statutes may or may not specify which edition of the AMA Guides to use and how to use them. Thirty-five states make use of the AMA Guides, and 60% (21) of them use the Fifth Edition. Eleven states use the Fourth Edition (Alabama, Arkansas, Delaware, Kansas, Maine, Maryland, Nevada, Ohio, South Dakota, Texas, and West Virginia). One state uses the Third Edition–Revised (Colorado), and one state uses the Second Edition (Louisiana). Some states use their own guidelines for specific issues and use the AMA Guides for other issues (eg, Washington State rates spinal impairment using the state's own guidelines but rates extremity disorders using the AMA Guides). Many states use a statutory schedule to assess amputations, hearing loss, visual loss, hernias, and disfigurement; some states may use a statutory schedule and use the AMA Guides for nonscheduled injuries. Physicians who practice in a state that does not make use of the AMA Guides in state workers’ compensation cases may need to assess impairment using the “latest edition” of the AMA Guides. The article includes a tabular summary of state statutes that deal with rating impairment in workers’ compensation cases.