Botulinum toxin-A, a neurotoxin derived from Clostridia Botulinum, has been injected into the laryngeal muscle(s) for the treatment of the spasmodic dysphonia at the Voice Clinic, Yonsei Institute of Logopedics and phoniatrics since December 1995. We analyzed 355 patients with spasmodic dysphonia, using Botox register review. In the 355 patients, female is 86.8%. male is 13.2%. 305 patients (85.9%) had adductor type of spasmodic dysphonia and 35 patients (9.9%) were vocal tremor type and 15 patients were abduction and mixed type. Botulinum toxin type-A (Botox) injection using EMG was most frequently conducted as 587 cases, comparing with flexible nasopharyngoscopy gudied injection (68cases) and tele- laryn-goscopy guided injection (31cases). In the respect of frequency of Botox injection, 137 patients(38.6%) were injected one time but 1 patient was injected 17times. The mean dose of Botox is 6.2U. Clinically, initial dose of Botulinum toxin-A was high dose (7-8U) but current dose is small dose (3U). And the mean duration of Botox injection is 6.4 month. In conclusion, to optimize effect of the treatment for spasmodic dysphonia, Botulinum toxin-A injection is combined with voice therapy.