In the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides), Sixth Edition, the chapter on the upper extremities is the longest and most complex, which reflects the complexities of the upper limb and the type of injuries encountered. This chapter incorporates the following changes: The International Classification of Functioning, Disability, and Health (ICF) Model of Functioning and Disability, developed by the World Health Organization, is used to provide a common basis for the description of human functioning and impairments. The principles of assessment have been simplified and clarified. Specific diagnosis-based rating tables for the most common injuries and diagnoses have been added, and an extensive discussion shows the definition of impairment classes and corresponding ranges of impairment for upper and lower extremities. A table and accompanying diagnosis-based impairment example provide examples of upper extremity diagnoses and associated class definitions and default impairment values. The physical examination has been simplified, and functional assessment is provided through focused history-taking, including information about activities of daily living and a functional assessment tool. The criteria for diagnosis of complex regional pain syndrome have been updated for consistency with current standards and other chapters. Among other modifications, the approach to entrapment neuropathy (eg, carpal tunnel syndrome) has changed, and only electrodiagnostically confirmed entrapment cases are ratable.