Botulinum toxin, a neurotoxin derived from Clostridia Botulinum, has been injected into the target muscle(s) for the treatment of several kinds of voice and speech disorders at the Voice Clinic, Yonsei Institute of Logopedics and Phoniatrics since December 1995. Criteria for the diagnosis and method of injection for spasmodic dysphonia, mutational dysphonia, muscle tension dysphonia, dysphonia after total laryngectomy, and stuttering were summarized. Among 144 patients with adductor type spasmodic dysphonia, who were injected one time to maximum 8 times during the 27 months, 90% were recognized as having better than slight improvement. Even though the injected cases were small, not only the abductor type spasmodic dysphonia, but also the intractable mutational dysphonia or muscle tension dysphonia resistant to voice therapy revealed that botulinum toxin injection would be another options for treatment. Patients who cannot phonate after total laryngectomy and some forms of adulthood stutterers can also be candidates for the injection of botulinum toxin.