A sample of the Baltimore population was interviewed in order to determine the frequency of symptoms suggestive of transient cerebral ischemic attacks. Respondents were interviewed in their homes. A history of ten symptoms which may have occurred within the past two years was elicited. Of the 6,830 individuals that were interviewed, 52% had no symptoms and approximately 10% had three or more symptoms. The frequency of symptoms did not increase substantially with advancing age between ages 45 to 74 or very markedly by sex and race. Individuals reporting a history of cardiovascular disease, stroke or diabetes had a substantially higher frequency of symptoms. Also the frequency of symptoms appeared to be higher in the less-educated groups.