The abnormality of gait that may occur in patients with subcortical arteriosclerotic encephalopathy (Binswanger's disease) is described in 12 patients in whom difficulty walking was the presenting symptom. Their gaits had elements of both Parkinsonism and ataxia, which were most marked in 4 patients unable to stand unaided. The difficulty in using their legs to walk was out of proportion to that of other movements of the lower limbs when lying or seated. In contrast, upper limb mobility and facial expression were relatively preserved. Attention is drawn to the similarity of this gait pattern to that of some patients with hydrocephalus, frontal lobe lesions, and "senile" disorders of gait. A possible mechanism for this Parkinsonian-ataxia in these various conditions may be their propensity to damage the afferent and efferent interconnections of the leg areas of the motor and supplementary motor areas of the cerebral cortex with, the cerebellum and basal ganglia.