To study the causes of lacunes (small cerebral infarcts) and the frequency of large brain infarcts in the same patients, the records of all patients admitted to the University of Utah Hospital between January 1983 and June 1986 with the diagnosis of acute cerebral or brainstem infarction were retrospectively reviewed. The neuroradiologist's interpretation of each patient's computed tomography (CT) scan was used to identify a cohort of 69 patients with lacunes. The medical records were examined for data pertaining to clinical events, and the CT scans were inspected to determine the dimensions and anatomic distribution of the infarcts. Patients who had larger infarcts or intracranial hemorrhages, in addition to one or more lacunes, were included. Twenty-seven patients (39%) were normotensive; 29 (42%) were hypertensive, and 13 (19%) had a history of hypertension but were normotensive at the time of the stroke. Ninety-five lacunes were distributed evenly among these three groups. The lacunes were larger in the normotensive patients. Twenty large infarcts were distributed evenly in the three groups. Diagnostic evaluation revealed significant abnormalities. The presence of cardiac and/or arterial disease places patients with lacunes at greater risk for more serious cerebral ischemic events and for recurrent small strokes. These observations are discussed as they relate to the causes and significance of lacunes.