Multivariate models have not been widely used to predict the outcome of acute stroke patients admitted to the intensive care unit (ICU). The purpose of this study was to determine potential measures observed in the first 12 h post-stroke that predict early mortality and functional outcomes in ICU-admitted stroke patients. Eight hundred and fifty acute stroke patients (ischemic stroke, 508; intracerebral hemorrhage, 342) were included in this analysis between November 2002 and December 2006. Measures of interest were obtained in the first 12 h after onset of stroke were analyzed for three types of outcome: 3-month mortality, 3-month mortality or institutional care, and poor functional outcomes at discharge. Poor functional outcomes were defined as a Barthel index <80 or a Rankin scale >2. Multivariate regression models were used to determine the predictive value of the observed measures. After 3 months, 17% of patients had died; 21% were alive but being cared for in institutional settings; and 62% were alive and living at home. Functional status at discharge indicated 16% of patients had died, poor function in 50%, and good function in 34% of patients. Initial stroke severity, measured by National Institute of Health Stroke Scale, and dependence on a ventilator predicts 3-month mortality and poor outcome in all stroke patients. In addition, old age, previous stroke, and total anterior circulatory infarct were associated with poor outcome in ischemic stroke patients; old age, low body mass index and the presence of intraventricular hemorrhage were associated with poor outcomes in intracerebral hemorrhage patients. In conclusion, early stroke mortality and outcome at discharge can be predicted in the first few hours following an acute stroke for moderate to severe ICU-admitted stroke patients.