We compared the performance of 40 patients with frontal lobe dementia to that of 40 patients with subcortical vascular dementia (80 patients including, 46 men and 34 women) in a set of tasks assessing attentional, executive, and behavioural tasks. The frontal lobe dementia represents an important cause for degenerative disruption and is increasingly recognised as an important form (up to 25%) of degenerative dementia among individuals of late-middle-age. The main involvement is the frontal-subcortical pathway, which is the final target of impairment even in subcortical vascular dementia. A wider involvement of the cortical (decisional) layers in frontal dementia, in contrast with the prominent and widespread involvement of the subcortical pathways (refinement and corrections programs) creates the different profiles of the two groups. Frontal patients have more difficulties in abstract reasoning, focusing attention, and implementing strategies to solve problems. They exhibit more profound behavioural alterations in personality and social conduct and show only moderate depression, and a total lack of insight concerning their dinical condition. In contrast, the patients with subcortical vascular dementia have poor general cognitive functions, high insight, and important depression and apathy as the principal and most salient characteristic of their behavioral conduct.