Distal median neuropathy is the most common entrapment neuropathy affecting the upper extremity. Although most often idiopathic, there are a large number of associated medical disorders. Electrophysiologic testing plays a central role in the diagnosis of distal median neuropathy in establishing localization; assessing severity; and excluding disorders of the proximal median nerve, plexus, and nerve roots which can mimic the clinical symptoms of distal median neuropathy. Treatment is usually successful, especially when diagnosis is established early in the course before any significant axonal loss has occurred.