Many methods of treatment are available for improving voice quality in unilateral vocal cord palsy patient, and the best one known until now, is Teflon or silicon injection, But the result was not satisfying because of unability to control the voice pitch. Never reinnervation procedures, assumed to be more physiological for improving the voice quality, have been experienced by many authors until now, but controversy of results exist among them. The purpose of this experiment is to prove that, the anastomosis of sectioned RLN(recurrent laryngeal nerve) and removal of the PCA(posterior cricoarytenoid muscle), the unique abductor muscle of the vocal cord, may improve the adduction capacity of the vocal cord, so improving the voice quality. Thirteen mongrel dogs were used for this experiment : 3 dogs with RLN sectioned, 3 dogs with RLN sectioned and PCA removed, 3 dogs with PCA removed and 4 dog with RLN anastomosed and PCA removed three months later, telelaryngoscopy with television monitoring, videolaryngography, nerve stimulation test, acoustic analysis and histologic evaluation were done, and results were as following : 1) In RLN sectioned group and RLN sectioned with PCA removed group, 3 months later, the vocal cord was still paralysed and only noise could be heard. So, PCA muscle removal without sectioned nerve anastomosis, does not improve the phonation sound. 2) In PCA removed group, 3 monthes after, the vocal cord was slightly more adducted, and sound analysis revealed that, the fundamental frequency remained unchanged, somewhat perturbation rate and intensity was slightly raised. So, PCA removal with intact RLN has only a slight effect on phonation. 3) In RLN anastomosed and PCA removel group, in immediate postoperative period, only noise without fundamental frequency could be heard, but 3 monthes after, a definitely improved phonation sound, somewhat with a decrease in fundamental frequency and intensity and an increase in perturbation rate, was heard. This results suggest that reanatomosis of the sectioned RLN and removal of the PCA was quite effective for improving the phonation in unilateral vocal cord paralysis in dog and this method may perhaps be applicated for the treatment of unilateral vocal cord paralysis in man.