Introduction: Ischemic stroke in young adults is a serious socioeconomic problem and a common cause of mortality and morbidity. The purpose of this study is to clarify pathogenic and clinical feature of ischemic stroke in young adults, based on the most common etiologies we can discuss about primary prevention in this range of age.Material and Methods: From February 1999 to January 2002, 106patients of consecutive admission in neurology ward of Ghaem hospital with ischemic stroke aged 15-45 years (55men, 51women) were studied. Sex, vascular risk factor including: hypertetion, diabetes mellitus, hyperlipidemia, smoking and OCP, cardiac source of emboli (emblogenic cardiac disease) and clinical categories of stroke were examined. Serologic test, CT Scan, MRI, angiography and echo Doppler of carotid and vertebral arteries transthorasic and transesophageal echocardiography were performed. Results: Men were slightly predominant in this study (52%men, 48%women). The youngest age was 15 years old but majority of patients were between 31-45 years (72.6%) of age. Following etiologies were obtained: 1) Cardiovascular emboli (52.5%), 2) premature atherosclerosis (11.3%) 3) Non atherosclerotic vasculopathy (2.8%),4) antiphospholipid antibody (1.9%),5) OCP (HO) consumption (1.9%), 6) Hereditary coagulopathy (1.9%) and 23.6% remained with unknown etiology. Out of 64 embologenic cardiac disease the most ftequent was rheumatic heart disease (42%) and other etiologies were MVP (26.3%), prosthetic valves (10.9%), PFO (patent foramen ovale) (6.2%), acute MI (4.7%),CHF(4.7%), endocarditic (4.7%)Conclusion: Patients < = 45 years of ages are likely to have various and unique etiologies for ischemic stroke. A specific diagnosis approach is strongly recommended for young patients with ischemic stroke, so it is necessary to look for and identify the source of cardiac embolism and initiate adequate treatment for prevention of recurrence.