We studied motor impersistence syndrome (MIS) in patients with a clinical diagnosis of probable Alzheimer's Disease (AD). MIS was found in 16 (10%) of the 166 patients examined; all 16 were moderately to severely demented (Mini-Mental State scores ranging from 17 to 2). We compared the neuropsychological features between these AD patients with MIS and AD patients without MIS matched by the severity of dementia. We found no significant difference between the two groups in terms of orientation, memory, language, attention, and visuoconstructional and visuoperceptual abilities. Buccolingual and limb praxis also failed to reveal differences between the groups. Although MIS has been related to visuoconstructional disorders and apraxia, the phenomenon as it occurs in AD seems not to be related to any specific cognitive domain.