Dystonia is a group of debilitating neurological movement disorders characterised by abnormal sustained or intermittent involuntary co-contraction of opposing muscle groups. While some forms of dystonia are caused by rare genetic mutations or acquired following a toxic or physical injury or other cause, the majority of cases arise with no clear aetiology. It is thought that these idiopathic dystonias manifest following a complex interaction between genetic susceptibility and non-genetic triggers. The inherited and idiopathic forms of dystonia share a number of symptomatic and physiological similarities. In addition, the genes linked to inherited forms of dystonia (‘DYT genes’) appear to influence many of the same cellular process, despite being functionally different. The causes of inherited or acquired dystonia may therefore provide clues to the aetiology of the idiopathic dystonias in the form of genetic and nongenetic risk factors for the disorder. The focus of this thesis is to identify risk factors for idiopathic dystonia to better understand the mechanisms of the disorder. All subjects examined in this thesis were recruited from movement disorder clinics in Queensland, Australia. A questionnaire was employed to assess possible risk factors for idiopathic dystonia. This questionnaire surveyed several factors pertaining to environmental exposures, lifestyle, medical history and family history of disease. Data obtained from 184 dystonia cases was compared with that of 242 matched controls and 1048 unmatched controls. The analysis of these risk factors revealed significant associations between and tremors, anxiety disorders, depression, head traumas and cigarette smoking and development of idiopathic dystonia.