The Semon-Rosenbach's rule of the vocal cords in recurrent nerve paralysis has been discussed for a long time by many authors, and it is recognized that this theory does not give a law which can be generally applied to all cases of recurrent nerve paralysis. In this work peripheral distribution of the laryngeal nerve, the laryngeal reflexes and the vulnerability of the recurrent laryngeal nerve was studied by using the electromyogram. 1) Peripheral distribution of the laryngeal nerve of man and dog was found to be anatomically and functionally similar. 2) The laryngeal reflexes evoked by stimulation of superior laryngeal nerve were studied and discussed. 3) The vulnerability of abductor nerve fibre and adductor of recurrent laryngeal nerve, to compression, cooling, drugs and torsion, was studied. It would be reasonable to conclude that abductor nerve fibre is more vulnerable than adductor. 4) Electromyograms were taken of each intrinsic larngeal muscles under a direct vision when the larynx and these muscles were exposed to view during the precedure of performing Woodman's laryngoplasty on 2 cases of laryngeal paralysis. It was found that, even in cases of abductor paralysis, muscular activity of the abductor muscles was still evident. The cause of the socalled bilateral abductor paralysis was discussed.