We compared the reliability of asymmetry of forearm rolling (rotation of one forearm around the other in front of the torso) as a sign of unilateral cerebral dysfunction with that of other standard clinical tests. We studied 62 patients with radiologically confirmed unilateral cerebral lesions and 20 control subjects with normal imaging. Asymmetric forearm rolling was the most sensitive indicator of unilateral hemispheric disease (85%). This simple test is a useful addition to the neurologic examination.