In a prospective series of symptomatic adult hydrocephalus characterized by gait disturbance, cognitive impairment, and/or urinary incontinence, 88 of 118 patients (75%) had additional akinetic, tremulous, hypertonic, or hyperkinetic movement disorders. Their prevalence was highest in patients with idiopathic normal pressure hydrocephalus (NPH) of the elderly (56/65 patients, 86%), and they were less frequent in patients with secondary NPH (10/15, 66%), with nonhydrodynamic atrophic/other hydrocephalus (20/33, 61%), and with obstructive hydrocephalus/aqueductal stenosis (2/5, 40%). Akinetic symptoms were found in 73 of 118 patients (62%), and the most frequent movement disorder was upper extremity bradykinesia (55%). Akinetic, tremulous, hypertonic, and hyperkinetic movement disorders were exclusively secondary to causes not related to hydrocephalus in 24 of 118 patients (20%). The proportion of patients with movement disorders not attributable to only such causes was highest in the idiopathic NPH group (44/65, 68%). Thirteen of 118 patients (11%) presented with a parkinsonian syndrome. There was evidence for coexistent Parkinson's disease in four of these patients. Parkinsonism was found to be secondary to NPH in five patients and was found improved after shunting. Akinetic symptoms in patients with NPH generally responded favorably to CSF diversion, which was evident in 80% of a subset of this group. Various other movement disorders did not show definite improvement. The high prevalence of bradykinesia and other akinetic symptoms in NPH and the beneficial effect of shunting on such symptoms suggest that NPH may cause a more generalized disorder of motor function.