stroke affects mainly people aged over 65 years, and atherosclerosis predominates as the main etiopathogenic factor in ischemic stroke (is). on the other hand, cardiac embolism and arterial dissection are the most frequent causes of is in patients aged less than 45 years. however, inappropriate control of traditional vascular risk factors in young people may be causing a significant increase of atherosclerosis-related is in this population. furthermore, a variety of etiologies, many of them uncommon, must be investigated. in endemic regions, neurocysticercosis and chagas' disease deserve consideration. undetermined cause has been still reported in as many as one third of young stroke patients.