Among 133 consecutive patients with the clinical diagnosis of vascular dementia there were 6 patients (4.5%) in whom dementia was judged to be associated with cerebral hypoperfusion due to cardiac arrhythmias and systemic hypotension. Patients with cardio-pulmonary arrest and resuscitation were excluded from this series. Our findings suggest that cerebral hypoperfusion is not an uncommon mechanism to contribute to the evolution of vascular dementia in the elderly. Besides arrhythmias, also hypovolaemia caused by diuretics medication might have been a contributory factor to hypoperfusion. It is evident that cerebral hypoperfusion is the predominant mechanism responsible for vascular dementia in some cases. It may be a contributing factor also in many cases of multi-infarct dementia. Thus, besides dementia after cardio-pulmonary arrest, vascular dementia of the haemodynamic type as a separate clinical entity is open to discussion.