26 patients with ataxic hemiparesis syndrome (AHS), due to acute ischemic cerebrovascular disease, have been submitted to clinical and electrophysiological evaluation, in order to assess the frequency of sensory disturbances in this condition. Sensory impairment were present in 78% and SEP abnormalities in 54% of the patients, while they were entirely absent in 23% of them. Lesions responsible for AHS, detected by CT scan, were mainly located in the thalamus, capsula interna, subcortical white matter, centro parietal cortex; sensory and SEP changes were more frequent in gross infarct involving the cortex and in smaller infarcts involving the thalamus, less frequent in the lacunar infarcts of the capsula interna and subcortical white matter, relatively rare in patients with CT scan without hypodense lesions. Although a statokinesthesic defect and/or major SEP abnormalities were often present (38% of patients), our findings do not support the view that they are involved in the pathogenesis of the ataxia, which may rather be attributed to a derangement of cerebro-cerebellar and cerebello-cerebral connections.