Background and Purpose: Stroke in young adults is relatively uncommon. Only 3.7-14.4% of all strokes occur in patients aged 15-45 years. Stroke in young adults has more various and diverse possible causes than stroke in the elderly. We studied to gain further insight into both pathogenic and etiologic determinants in young adults with stroke. Methods : We retrospectively reviewed the medical records of 230 young patients aged 15-45 years who were admitted to the 2nd internal medicine department of Kyung Hee Oriental Medical Center with a diagnosis of stroke between May 1995 and May 1999. We analysed clinical features and diagnostic tests, such as brain imaging, cerebral angiography, echocardiography, 24 hours holter monitoring and other laboratory tests. Results : 1. Of 230 young patients with stroke aged 15-45 years(176 males(76.5%) and 54 females(23.5%)), 140 patients(60.9%) showed ischemic stroke and 90 patients(39.1 %) showed hemorragic stroke. 2. The most prevalent age group was from 40 to 45 years with 142 patients(61.7%) 3. The most frequent site of 140 ischemic stroke was MCA territory in 93 cases(66.4%) and Multiple, VA territory, PCA territory, ACA territory in order of frequency. 4. The most frequent site of 90 hemorrhagic stroke was basal galglia hemorrhage 57 cases(63.3%) and subcortical 13 cases(14.5%), pons, thalmus, subarachnoid, cerebellum in order of frequency. 5. The causes of hemorrhagic stroke were hypertension 49 cases(54.5%), arteriovenous malformation 7 cases(7.8%), ruptured aneurysm 4 cases(4.5%), angioma 3 cases(3.3%). 6. The risk factors of ischemic stroke were smoking, alcohol drinking, hyperlipidemia, hypertension, obesity, heart disease, history of CVA, diabetes mellitus, in order of frequency. 7. The comparison of risk factors between ischemic and hemorrhagic stroke: hypertension was prevalent in hemorrhagic stroke, heart disease and history of CVA were prevalent in ischemic stroke. Conclusions: From the above results, we found that stroke in young adults had various possible causes. Young adults with stroke deserve an extensive but tailored evaluation which include angiography and echocardiography for diagnosis.