We compared the relative elevations of the two diaphragms in the supine chest films of 62 patients with recent hemiparesis due to a supratentorial stroke with that of 92 acute coronary patients without neurologic disease. Patients with severe hemiparesis or lesions larger than 40 ml exhibited an excessive elevation of the diaphragm on the paretic side compared with controls. This finding was more common with lesions involving the genu of the internal capsule and/or the near anterolateral area. Measurement of the interdiaphragmatic elevation difference may give information on the location and/or size of the stroke.