Cerebral infarction before the age of 45 years accounts for 4-6% of all strokes. The etiology remains unexplained in a significant proportion of patients even after extensive investigations. The reported risk factors of this age group are cardiopathies, hypertension, smoking, hypercholesterolemia, reduction of anticoagulant proteins, hypercoagulable states, antiphospholipid antibodies primary syndrome, antiphospholipid antibodies secondary syndrome, some hemoglobinopathies, hyperviscosity syndromes, vasculitis, collagen vascular diseases, fibromuscular dysplasia, arterial dissections, migraine, myopathy encephalopathy lactic acidosis stroke like episodes, homocystinuria, familial amyloid angiopathy, microangiopathy with retinopathy encephalopathy and deafness, systemic lupus erythematosus, use of cocaine, traumas or manipulations of neck, AIDS. From 1/1/94 to 04/30/95 we observed 19 patients with cerebral infarctions and 9 patients with transitory ischemic attacks in young people. The aim of our study was to apply a diagnostic protocol by sequential tests of first level and second level. According to this protocol we found that the more common risk factors were ischemic cardiopathy, hypertension, smoking and hypercholesterolemia. Moreover we observed other independent risk factors, although less frequent, like the antiphospholipid antibodies, neurolupus, AIDS, deficit of protein S.