Stroke patients were assessed by brain CT scan, accompanied by demographic and clinical factors to predict the development of dementia following an ischemic episode. Vascular dementia was defined by NINDS-AIREN criteria. From 50 demented and 50 non-demented stroke patients, we analyzed the location of lesion, counted the numbers of lacunae, and semiquantitatively assessed the size of infarction, severity of overall white matter lesions (WML), and degree of brain atrophy. Compared to the non-demented patients, the demented patients: 1) encountered more stroke episodes (p < 0.001); 2) had more lacunae at bilateral basal ganglion (p < 0.001) or thalamus (p < 0.01); and 3) tended to have lesions in left cortex (p < 0.001), particularly a large infarct at the parietal (p < 0.001) or temporal lobe (p < 0.001). Periventricular changes (p < 0.001), subcortical WML (p < 0.001), overall WML (p < 0.001), and brain atrophy (p < 0.05) were also more severe in the demented group. However, no difference existed in demographic factors between the two groups. We concluded that several factors were important in developing dementia following an ischemic stroke, and the order by logistic regression would be: the severity of overall WML, left parietal infarct, and numbers of thalamic lacunae.