Botulinum toxin A has a wide variety of clinical applications, which are related by blockade of acetylcholine and often are related to abnormal muscle contractures. These applications include ocular disorders, disorders of the upper aerodigestire tract, dystonia and hemifacial spasm, cosmetic, gastrointestinal disorders, genitourinary disorders, management of pain, and use in autonomic nervous system disorders. Many of these diseases will be discussed with regard to their treatment with botulinum toxin compared to conventional treatments. Advantages and disadvantages of botulinum toxin use are delineated. General guidelines for adult and pediatric dosing will also be discussed.