Dystonia is a heterogeneous, neurological disease characterized by involuntary, sustained muscle contractions, frequently causing twisting and repetitive movements or abnormal postures. The patients are often difficult to diagnose, and the treatment is almost always only symptomatic. It is believed that about 75% of all patients with dystonia have primary dystonia, and 25-85% of these are hereditary. Seven gene loci for autosomal, dominant inherited dystonia and two for X-linked, recessive inherited dystonia are known at present, but the underlying genes are known only for DYT1 and DYT5. Testing is possible for these two in Denmark. Growing molecular genetic knowledge will lead to earlier and correct diagnosing, including prognosis, and may elucidate the pathogenesis, making better treatment possible.