A total of 969 (73%) of 1,328 patients with cases of suspected transient ischemic attacks (TIAs) who came to six institutions during a 21-month period were followed up. Factors were identified and prospectively analyzed for risk for further TIAs, stroke, and deatn. A history of multiple carotid artery TIAs was significantly related to further TIAs. A single TIA placed the patient at greater risk for early infarction. Older age, male sex, and unreliability to take dangerous medication were risk factors for cerebral infarction. Anticoagulant therapy, older age, male sex, diabetes mellitus, heart disease, abnormal ECG, and poor surgical risk were factors for death. The increased mortality associated with anticoagulants was confined to the older age group. While white patients treated with antiplatelet-aggregating agents had a lower mortality than those treated otherwise, this was not true amont black patients.