To gain insight into the historical features relevant to the diagnosis of cardiac embolie strokes, we studied the 1,290 patients with cerebral infarcts in the NINCDS Stroke Data Bank. Based solely on the presence of cardiac sources of embolism, we divided the patients into groups of high (n = 250), medium (n = 166), and low (n = 874) risk of a cardiogenic mechanism for their stroke. There was a highly significant graded relationship between increasing risk of a cardiac source and a history, or presence of, systemic embolism, abrupt onset, and diminished level of consciousness at onset. These clinical features may be useful for assessing the likelihood of a cardiac embolie mechanism in patients with cerebral infarcts.