STUDY DESIGN: Literature review. DISCUSSION: Botulinum toxin A, a neurotoxin causing temporary muscle paralysis at the neuromuscular junction, has been used to treat multiple acquired conditions of the hand and upper extremity. Initially approved for use in treating blepharospasm and strabismus in the 1980s, indications have expanded to include spasticity associated with cerebrovascular accidents, vasospastic disorders, focal dystonias, and pain conditions. This article reviews the current literature discussing the efficacy of botulinum toxin A in management of disorders of the hand and upper extremity relevant to hand therapists.