Vascular pseudoparkinsonism may be confused with idiopathic Parkinson's disease. Patients may be unnecessarily treated with anti-parkinsonian drugs while their underlying vascular disease is ignored. We investigated 250 parkinsonian patients seen in our Movement Disorders Clinic for a possible vascular etiology. After excluding those with a known secondary cause such as drug-induced parkinsonism, progressive supranuclear palsy, multiple system atrophy and hyperparathyroidism, brain computed tomography and/or magnetic resonance imaging were performed on those who showed poor or no response to levodopa. In those with an ischemic lesion demonstrated on neuroimaging, anti-parkinsonian drugs were stopped and the patients were reassessed. Eleven patients (4.4%) had ischemic brain lesions accounting for their parkinsonism. All were initially diagnosed as Parkinson's disease because of the prominence of bradykinesia and rigidity. Gait disturbance was also common, but resting tremor was distinctly absent. Three anatomical patterns with different prognosis were identified. Three patients with basal ganglia lacunar infarct recovered spontaneously, three with frontal lobe infarcts remained static and five with periventricular and deep subcortical white matter lesions had progressive deterioration. Autopsy in one patient confirmed bilateral frontal lobe watershed infarcts and the absence of brain stem Lewy bodies. Parkinsonian patients with poor or no response to levodopa therapy should be investigated for a vascular etiology.