SUMMARY Transient ischemic attacks are the most important warning symptoms of impending stroke. They occur in up to one-half of all patients who develop stroke but, unfortunately, less than half of the patients who have them seek help from their physicians before stroke occurs. Physicians should regularly question patients about the possibility of such symptoms and patients with them should seek prompt help. When transient ischemic attack is diagnosed, patients should be evaluated for elevated blood pressure, hyperlipidemia, cardiac dysrhythmia, cardiac disease, anemia, polycythemia and thrombocytosis. When these conditions are found they should be treated. Patients with carotid system TIAs should be evaluated clinically and radiologically for evidence of vascular disease. The neck should be auscultated for bruit and absent pulses and the peripheral vessels palpated. Patients with carotid system TIAs should have angiography of all 4 cerebral vessels and the angiogram should be evaluated for the presence and number of arterial stenoses and the presence of ulcerated plaques. When patients with carotid system TIAs are found to have localized extracranial atherosclerotic obstruction or ulcerated plaques in a vessel appropriate to the side of their symptoms of cerebral ischemia, they should be considered for prompt surgical correction of the lesion. For patients with carotid system TIAs, who have multiple sites of extracranial vascular disease, medical treatment is advisable with either anticoagulants or platelet antiaggregating agents. In view of the recently reported favorable results using aspirin in the prevention of TIA and stroke, this agent may be preferable to anticoagulants in instances where hypertension, patient compliance and laboratory facilities are a problem.