The use of diagnostic tests, the accuracy of stroke type diagnosis, and their relationship to outcome are important from the standpoint of patient management and health care costs. To address this issue, we examined the differences between stroke types in terms of demographics, risk factors, diagnostic tests, and clinical outcome in the 4,129 patients who comprise the Community Hospital-Based Stroke Program. Previous transient ischemic attacks were equally frequent among patients with embolic and those with thrombotic stroke. For all stroke types, previous stroke was as frequent as previous transient ischemic attacks. Hypertension and cardiac disease were the most common risk factors, but 10% of all stroke patients had no recognized risk factors. Intracerebrai hemorrhage was most often associated with death (45%). There was a strong direct relation between in-hospital mortality and a decreased level of consciousness at admission. Overall, 30% of patients did not receive a specific stroke type diagnosis; these patients were elderly, usually nonwhite, and often had an altered level of consciousness at admission but had a risk factor profile similar to that of patients who received a specific stroke type diagnosis. In summary, our findings suggest the continued need for physician education about and refinement of stroke type diagnosis. © 1990 American Heart Association, Inc.