Vocal cord paralysis is a comlex disorder which may result from numerous causes. It is often associated with trauma, disease in adjacent tissue, or a generalized neuroligical disorder. Laryngeal EMG is a useful technique for vocal cord paralysis. However it has not been used due to the uncertainties of normal human vocal cord physiology and the technical difficulties in performing these studies. We investigated the pathophysiology of vocal cord paralysis with laryngeal electromyography(LEMG). We studied 20 patients with idiopathic vocal cord paralysis. 6 patients were denervated in the cricothyroid(CT) and 6 patients in the thyroarytenoid(TA), and 3 patients in both CT and TA muscles. These indicated superior laryngeal neuropathy, recurrent laryngeal neuropathy, and proximal laryngeal or vagus neuropathy, respectively. LEMG proved to be a safe and effective procedure in the diagnosis of laryngeal neuropathy, and make it possible to use electromyography as a routine procedure in diagnosis laryngeal paralysis.