Diaphragmatic palsy in hemiparetic stroke is not well recognized. Further, its implications on stroke outcome have not been studied. Here, we report a patient with left-sided diaphragmatic palsy due to an acute right middle cerebral artery territory infarction. The diagnosis was suspected on finding an elevated dome of the diaphragm on the left side in a routine chest radiograph and was confirmed by finding decreased movements of the left hemidiaphragm on fluoroscopic examination. We hypothesize that this condition is probably under-recognized in clinical practice and its clinical importance not well known. The pathophysiological basis of diaphragmatic palsy in acute stroke and its possible clinical implications are discussed.