Stroke is the fifth leading cause of death and a common serious neurological problem. The location of a presumed ischemic lesion can be inferred by relating the observed signs and symptoms to the functional anatomy of the cerebral vessels. It is essential to be able to determine whether a lesion lies in the distribution of either the carotid or the vertebrobasilar arterial systems. The focus of this paper will be limited to a discussion of strokes occurring within the distribution of the vertebrobasilar system. Although nursing does not make medical diagnoses, a clear understanding of the clinical presentation and potential problems will enhance the nurse's ability to develop a comprehensive plan of care for the patient.