A case of presenile dementia with dominant frontal disfunction, progressive aphasia and Motor Neuron Disease with prominent bulbar signs is reported. Considering the clinical examination, the measurements of the regional cerebral flow (SPECT) and the histological appearances, we suggest the diagnosis of Dementia of Frontal Lobe Type and Motor Neuron Disease. We reviewed other disorders labelled Primary Frontal or Fronto-temporal Dementias and we discuss this new dementia and the difficulty in its classification.