Spatial disorientation was investigated in 28 ambulatory patients meeting the National Institute of Neurological Disorders and Stroke-Alzheimer's Disease and Related Disorders Association Work Group criteria for "probable" Alzheimer's disease. Based on caregivers' reports, 39% of subjects engaged in at least three of four behavioral measures of spatial disorientation three or more times a week; these patients did not significantly differ from other Alzheimer's disease subjects with regard to age, sex, education, or symptom duration. Using stepwise regression analysis, we found that neuropsychologic measures of memory and visuoconstructive functions, but not disease severity, attention, or language impairment, emerged as significant predictors of spatial disorientation. In the setting of impaired memory, the tendency of some patients with Alzheimer's disease to wander or to get lost may implicate particularly severe dysfunction of right hemisphere neocortical areas concerned with visuospatial processes.