Case exercises are an effective way to increase one's understanding of the appropriate application of the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides). Following is one of more than seventy cases that are included in the new edition of The Guides Casebook. This case illustrates the process of assessing impairment for carpal tunnel syndrome using the fourth, fifth, and sixth editions. In this case, a 45-year-old woman who packed boxes on an assembly line developed insidious onset numbness and tingling in her right, dominant hand. A nerve conduction study was consistent with a sensory conduction delay, and she underwent a carpal tunnel release. Physical examination revealed normal monofilament testing and normal two-point discrimination (5 mm) in all digits, and focal muscle testing results were normal, without atrophy. According to an assessment using the fourth edition, 0% whole person impairment was given because no objective evidence showed ongoing sensory or motor deficits. According to the AMA Guides, Fifth Edition, the patient would receive a 1% whole person impairment because in the past the diagnosis of carpal tunnel syndrome was confirmed by electrophysiological studies. Use of the sixth edition yields 1% whole person impairment on the basis of the patient's QuickDASH score of 0 and, providing her with the benefit of the doubt, one would assign the lowest impairment for grade modifier 1, ie, 1% whole person impairment.