Motor behaviors on the 'good side' of the body, i.e. ipsilateral to the hemispheric lesion, have not been studied systematically. We assessed motor behaviors in 20 consecutive patients during the acute phase (first 1-2 weeks) of a hemispheric stroke with hemiparesis. The behaviors were essentially rotations of the head, neck, eyes and trunk, orofaciopharyngeal or limb stereotypes, compulsive manipulation of the surroundings, or passive mobilization of the paralyzed arm or leg. These behaviors were found only with large infarcts in the territory of the internal carotid artery, middle cerebral artery and/or the anterior cerebral artery (ACA). All but two ACA infarcts involved the internal capsule and basal ganglia. The severity of the motor deficit and the presence of aphasia, neglect, or sensory loss were significantly correlated with the motor behaviors. Although the understanding of these behaviors remains unclear, we suggest that they may represent the clinical expression of early plastic changes of brain maps and circuits after an acute lesion; this is probably an active process induced by disinhibition, in order to establish new compensatory pathways.