In previous reports, many predictors of early deterioration after ischemic stroke have been proposed and studied, yet the results remain controversial. For example, several studies have been performed to ascertain whether cerebral or systemic causes are the major determinants of stroke deterioration. The findings, however, have been inconsistent. Measures of overall status and stroke severity (low initial Canadian Stroke Severity score, low initial National Institutes of Health Stroke Scale score, early CT findings of stroke severity, and changes in cerebral blood flow affecting the ischemic penumbra as measured by positron emission tomography and single photon emission computed tomography imaging have been shown to predict early deterioration. Laboratory tests for coagulation markers (fibrinogen, D-dimers), inflammatory markers (increased interleukin-6, decreased interleukin-10), serum glucose at admission, hematocrit and physiological parameters, such as blood pressure (both elevated and decreased), and body temperature have been identified as predictors of early deterioration. In addition, patient medical history (diabetes mellitus, atherosclerosis, chronic heart disease) has also been associated with early stroke deterioration. These differing findings may be due to variations in study design, patient populations, selection and exclusion criteria, and the criteria used for defining early deterioration.