The posterior cricoarytenoid muscle shows different physiologic characteristics and enzyme profile from those of many other muslces. This muscle is a sole abductor muscle of the larynx and has a important function to manintain inspiration. Although data available for the canine PCA indicate that it has different muscle fiber type composition from that of other mammalian muscle, there is yet no information available concerning the changes of muscle fiber composition after laryngeal reinnervation. Since these data are essential to an understanding of the physiology and suitability of reinnervation procedures, we have examined the distribution of the muscle fiber types using histochemical technique. Using ATPase stain(pH 9.4), normal PCA was composed of 51% type I fibers and 49% type II fibers. After reinnervation, PCA showed muscle fiber type grouping and minimal increase of type II fibers. This change was less than 5%, so it may not affect of vocal cord abduction after reinnervation.