Fifty-two stroke patients, 43 with cerebral ischemia and nine with cerebral hemorrhage, underwent continuous cardiac monitoring in an Intensive Stroke Care Unit shortly after the onset of the acute cerebrovascular accident. In the group of patients with no evidence of pre-existing heart disease, eight of 18 with cerebral ischemia and five of seven with hemorrhage developed ECG abnormalities. Additional ECG changes were noted in 21 of 25 patients with cerebral ischemia and two of two with hemorrhage who were known to have previous heart disease. Both disturbances in rhythm and conduction and “ischemic” ST-T alterations were detected and the frequency of the former exceeded that of the latter. The ECG alterations were transient in 32 patients and permanent in four. New electrocardiographical abnormalities in patients without evidence of heart disease prior to the stroke were associated with poorer prognosis. The pathogenetic mechanisms leading to the appearance of cardiac abnormalities in stroke patients are considered.