The causes of ischaemic brain damage are numerous. Four main groups are described: atherosclerotic disease of the cervical and intracranial arteries represents 50% of the causes, small vessel disease with lacunar infarcts 25%, cardio-embolic disease 20% and non-atheromatous arterial disease and blood dyscrasias 10%. In 10% of cases, no etiology is identified. MRI has a dominating place in the etiologic assessment of cerebral infarction, by distinguishing the various types of infarction, detecting associated abnormalities like leukoencephalopathy and haemorrhage and by analyzing the lumen and wall of vessels.