Botulinum toxin injection for treatment of facial wrinkles is the most frequently performed cosmetic procedure in the United States, and it is one of the most common entry procedures for clinicians seeking to incorporate aesthetic treatments into their practice. Treatment of frown lines and crow's feet, which are the cosmetic indications approved by the U.S. Food and Drug Administration, and horizontal forehead lines, offers predictable results, has few adverse effects, and is associated with high patient satisfaction.