OBJECTIVE A retrospective study of ischaemic and haemorrhagic cerebral vascular accidents in patients under 45 years of age, admitted to hospital Severo Ochoa (Area sanitaria 9 de la Comunidad de Madrid) during a 6 year period. METHOD 23 CVAs in women and 29 in men were studied. The aetiology of each episode was determined following preestablished criteria. RESULTS Aetiology: cardiac 13 (25%), atherosclerosis: 8 (15%), haematological: 6 (11%), non-atherosclerotic: 8 (15%), migraine: 1 (2%), hypertensive: 2 (3%), unknown: 15 (29%). There was a predominance of men in the patients with atherosclerosis. These also had more cardiovascular risk factors and were older than the other patients. All patients with CVA due to antiphospholipid antibodies had multiple CVAs. Examinations used to establish the aetiology were: echocardiogram, angiography, carotid doppler, hypercoagulability studies and the clinical history. CONCLUSIONS In spite of extensive study, 30% of the CVAs in young people still have no aetiological diagnosis. In general in ischaemic CVAs, there is good recovery of the neurological defects and a low mortality. The detection and oral anticoagulation of patients with a source of cardiac emboli, and the elimination of cardiovascular risk factors would probably considerably reduce the incidence of ischaemic stroke in young adults.