Forty patients with episodes of transient neurological dysfunction lasting less than 24 hr had abnormal CT scan findings. Eight patients had intracranial mass lesions and 32 had vascular lesions i.e. ischemic, infarction, hematoma. Seventeen patients had hypodense lesions consistent with tissue infarction; whereas 12 patients had isodense enhancing lesions consisting with tissue ischemia. In eight patients with isodense enhancing lesions, this was no neurological deterioration following carotid endarterectomy. In 3 patients who had transient ischemic attacks with CT evidence of hypodense lesions there was clinical and CT deterioration following carotid surgery.