According to the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides) the impairment rating of patients with Carpal Tunnel Syndrome (CTS) begins with a documented, objectively verifiable diagnosis by nerve conduction testing and is not based on symptoms only. A motor latency of more than 4.0 msec or a sensory latency of more than 3.7 msec clearly defines CTS, but the relative slowing of the median nerve should not be the basis of a CTS diagnosis for an impairment rating. After correct diagnosis, the next consideration is rating the impairment of patients with CTS who have not had surgery. The AMA Guides provides tables that summarize the calculations of common impairments and typically involve the maximal value of the median nerve's loss of function times a severity multiplier. Examples show the calculations for examples of impairment, including complete transection of the median nerve at the wrist, with and without severe reflex dystrophy (causalgia); a patient with CTS who has decreased two-point recognition (7-15 mm) but normal motor function, with and without normal sensation on two-point testing and no motor weakness. The article also discusses the questions that should be answered to determine if a patient who has had surgery for CTS has a permanent disability.