Dystonia is a movement disorder characterized by sustained or intermittent muscle contractions. Classification of dystonia is based on age of onset, distribution of body parts affected, and underlying etiology. A large number of different genetic forms of dystonia have been discovered in recent years. Although these syndromes are important to recognize, the majority of dystonias encountered in clinical practice are of unknown cause. Therapy of dystonia includes medications, particularly anticholinergic drugs, use of botulinum toxins, and deep brain stimulation.