Young normals, aged normals, and patients with early and advanced probable dementia of the Alzheimer type (DAT) were administered a facial recognition memory task. A continuous recognition paradigm was used, in which subjects were instructed to identify the repeated faces in an ongoing series of faces presented on a video monitor screen. A signal detection analysis of the data revealed that the DAT patients were markedly impaired in their ability to discriminate between new and repeated faces. Multiple presentations of faces improved the recognition accuracy of the early DAT patients only, but their rate of learning was slower than that of the normal subjects. In comparison to the young normals, elderly normals exhibited a mild deficit in recognition memory. All of the elderly subject groups exhibited a more liberal response bias than the young normals, which eliminates the possibility that the impaired memory task performance of the aged subjects could be attributed to a more conservative test-taking strategy. The DAT patients exhibited impaired recognition even when the second presentation of a face immediately followed the first, which perhaps implies that task performance was also sensitive to the effect of DAT on visuoperceptual abilities or psychomotor speed.