The electrodiagnosis of carpal tunnel syndrome (CTS) is reviewed, including discussions of old and new techniques of motor and sensory nerve conduction, anomalous innervation, and needle electrode examination. A variety of sensitive nerve conduction studies (NCSs) are available for the evaluation of a patient with suspected CTS. For any particular patient, the NCS method chosen by the clinical neurophysiologist may vary for a number of reasons, including the severity of the deficit and the presence of superimposed conditions.