We studied the clinical characteristics of transient global amnesia (TGA) in 277 patients with an average follow-up of 80 months. The syndrome occurred most frequently after age 50. There was a history of migraine in 14.1% and cerebrovascular diseases in 11.2% of patients, but these conditions were usually not temporally linked to TGA. Characteristic antecedent events and activity such as exertion existed in 33.4%. The incidence of TGA was 5.2 per 100,000 per year in Rochester, MN. Although 23.8% of the patients had recurrent episodes, they were not at increased risk for subsequent stroke.