Frey syndrome is characterized by profuse facial sweating which is provoked by the taste of food. It has been described as a consequence of upper thoracic sympathicotomy. Botulinum toxin injection is a relatively new treatment modality for Frey syndrome. Botulinum toxin type A (Botox, Allergan, USA) had been successfully used to treat Frey syndrome occurring in a 38-year-old patient following thoracic sympathicotomy for palmar hyperhidrosis. A total dose of 100U of botulinum toxin (1.0U/0.1ml/㎠) injection resulted in a 6 months` resolution of sweating, burning, and flushing sensation on eating. During the follow-up period, no systemic side effects were experienced.