The use of phonosurgery in the recent development of laryngomicrosurgery has enabled the restoration of normal voice in respect to functional laryngeal surgery of Korea, limited to simple removal of benign laryngeal tumor such as laryngeal polyps and Teflon intracordal injection for the treatment of recurrent nerve paralysis under the vision of suspension laryngoscopy. Operation of phonosurgery for the treatment of cord paralysis, vocal cord atrophy, spastic dysphonia and sulcus vocalis is a happy event in the view point of development of phonosurgery in Korea. In this aspect, the thyroplasty changing the position and physical characteristics of the cord outside the glottis instead of the direct handling of the vocal cord through direct endoscopy is popular. Among the 4 types of thyroplasty, classified by Isshiki (1974), thyroplasty type I (lateral compression of vocal cord) was effective in the treatment of unilateral vocal cord paralysis. Advantages of this operation are the fine adjustment of the degree of lateral compression under local anesthesia according to the phonation of the patient during operation and avoidance of dyspnea and intralaryngeal hemorrhage due to the manipulation outside the internal perichondrium of the thyroid cartilage. The author experienced 7 cases of thyroplasty type I for unilateral vocal cord paralysis during 6 months from September 1981 to February 1982. Before and two months after the operation, evaluations for aerodynamic study, psychoacoustical evaluation, stroboscopy and sound spectrographic analysis were done and the following results were obtained. 1) In the aerodynamic study, the maximum phonation time increased to 158%, Phonation Quotient and mean air flow rate were decreased to 63% and 48% of each preoperative value. 2) The degree of hoarseness improved in the psychoacoustical evaluation and the glottic chink during phonation was decreased in the stroboscopic examination. 3) In the sound spectrographic analysis, the periodicity was much restored and noise distribution decreased especially in the high frequencies.