Cerebral infarction in young people is considered a rare event. There are many potential etiologies capable of causing a cerebral infarction in this age group. Three hundred consecutive patients younger than 40 years with cerebral infarction were extensively evaluated. One hundred and sixty-two women were included in this study, most under 30 years. The most frequently encountered risk factors were tobacco and alcohol use, and rheumatic valvular heart disease. Etiologies for cerebral infarction in the order of frequency were: cryptogenic 32%, nonatherosclerotic vasculopathy 27%, cardioembolism 24%, hematological disturbance 10% (including 11 patients with deficiency of natural anticoagulant proteins), premature atherosclerosis 3% and migraine 3%. Our paper demonstrates that atherosclerosis is an uncommon cause of cerebral infarction in patients under 40 years. The principal etiologies were rheumatic valve disease, arterial dissections and prothrombotic states.