We investigated if, in patients with vascular lesions, the variable that best discriminated demented from non-demented patients was the severity of the vascular pathology or the degree of hippocampal atrophy. A total of 39 patients multiple subcortical infarcts, who could be considered as possible vascular dementia with small vessel pathology, with underwent a neuropsychological study and brain magnetic resonance imaging (MRI) DSM IV criteria supported by neuropsychological data were used to distinguish demented from non-demented patients. The MRI study took into account the degree of hippocampal atrophy (hippocampal height and interuncal distance) and the severity of vascular pathology (number of brain infarcts). The distribution of lesions and a factor analysis showed that hippocampal atrophy is a better predictor of dementia than the number of brain infarcts. Multiple subcortical infarcts alone are probably not able to cause clinical dementia but the presence of vascular lesions increases the expression of concomitant Alzheimer's disease.