The authors investigated the prevalence of DIS-ascertained DSM-III psychiatric disorders occurring in 28 patients with dystonia and 28 patients with Parkinson's Disease (PD). In patients with dystonia, lifetime prevalences of major depression (25.0%), bipolar disorder (7.1%), atypical bipolar disorder (7.1%), social phobia (17.9%), and generalized anxiety disorder (25.0%) were significantly more common than in epidemiologic catchment area (ECA) study population controls (p < 0.005). Social phobia and generalized anxiety disorder preceded dystonia (primary), while bipolar disorder developed after dystonia onset (secondary). In PD patients, the lifetime prevalence of simple phobia (35.7%, p < 0.0001) and atypical depression (21.4%) were significantly more common. Parkinson's Disease was associated with primary simple phobia and secondary atypical depression. These findings are considered in light of previous results and in terms of the differences in pallidothalamic physiologies in dystonia and PD. These data suggest distinctive profiles of psychiatric disorders in dystonia and PD.