With reconsideration of the role of vascular risk factors for Alzheimer's disease (AD; Gorelick et al., 1996), and with a recent Consortium to Establish a Registry for Alzheimer's Disease (CERAD) report that pure vascular dementia may be more difficult to find than has been widely assumed (Hulette et al., 1997), it is appropriate to reevaluate our understanding of so-called mixed dementia, or the dementia syndrome that arises from the combination of AD and ischemic vascular injuries. Such a reevaluation leads to potentially important lessons, an outline of which is presented here.