Background: This prospective study investigated the efficacy of injection laryn-goplasty in the management of postthyroidectomy vocal cord paralysis (VCP). Methods: From March 2005 to December 2008, 174 consecutive injection laryngoplasties were performed in patients with unilateral glottic insufficiency. This included 34 patients with post-thyroidectomy VCP: 15 with temporary VCP and 19 with permanent VCP. Percutaneous injection was performed under local anesthesia into the vocalis muscle, using disposable 25G-long needles through the cricothyroid membrane or directly through the thyroid cartilage. Patients completed the acoustic, aerodynamic, perceptual, stroboscopic, and voice handicap index evaluations before and at 3 and 6 months after the injection. Results: All injection laryngoplasty could be performed under local anesthesia without morbidity. Acoustic and perceptual parameters (overall grade of hoarseness, roughness, breathiness, asthenia, and strain), maximum phonation time, jitter, and shimmer, voice handicap index, and grades of mucosal waves and glottic closure were significantly improved after the injection and they remained stable over 6 months in both the temporary VCP and permanent groups (p < 0.05). Conclusions: Based on these preliminary results, injection laryngoplasty improved the voice, and voice-related quality of life in patients with post-thyroidectomy VCP. It is a simple, safe, and useful method for rehabilitating post-thyroidectomy VCP patients.