An ischemic stroke (IS) group including 386 patients under 50 years old is analysed taking into account different etiological subgroups and comparing risk factors against a control group of 100 people. The series points out the presence of 66.1% patients included in the inconclusive-atherothrombosis group, of which 22.7% had defined criteria of atheromatosis, while 11.6% were diagnosed of lacunar infarct. 13.5% of cases were considered as cardiac origin embolisms, and 14.1% were affected of mitral valve prolapse. The migraine group includes 4.9% of the patients while 17.6% belong to the miscellaneous group. The comparison of each of these groups with the control group showed significant differences for family history of stroke, personal history of peripheral arteriopathy, tobacco, arterial hypertension and previous IS.