The etiology of ischemic stroke affects its prognosis, outcome and management. Our aims were to determine risk factors, clinical and imaging variables and prognostic differences in acute ischemic stroke subtypes. In this study, we prospectively investigated 264 consecutive patients with acute ischemic stroke between 1996 and 2000. All of the patients were categorized to one of four major ischemic stroke subtype based on TOAST (Trial of Org 10172 in Acute Stroke Treatment) criteria. The mean age was greater in patients with stroke of undetermined etiology (SUE). Prevalence of hypertension was higher in patients with lacunar infarct (LAC) than other subtypes. Smoking was less frequent in patients with cardioembolism (CARD). The mean infarct size was largest in patients with large artery atherosclerosis (LAA) while there were no differences in location or conversion of the infarct into hemorrhage. The proportion of the patients with milder neurological deficits at entry was higher in patients with LAC subtype. The rate of independent patients were different between subtypes: 62% in LAC, 43% in CARD, 38% in SUE, 35% in LAA at discharge (p=0.01), and 91% in LAC, 69% in CARD, 59% in SUE, 60% in LAA at 6 months (p<0.001). Recurrence rates were not different between groups. We conclude that risk factors, clinical imaging variables are different among ischemic stroke subtypes and that neurological status on admission and during follow-up strongly favors LAC.