Patients with Huntington's disease (HD) were compared on three tests of remote memory with patients with alcoholic Korsakoff's syndrome (KS) and with control subjects. Though both patient groups were severely impaired in overall performance with respect to the normal control subjects on all three tests, striking differences were evident in the degree of loss for each decade interval. The patients with HD had as much difficulty identifying faces and events from the 1930s and 1940s as faces and events from the 1960s and 1970s. Thus, the pattern of their remote memory loss was "flat", that is, equal for all periods sampled. The retrograde amnesia of the patients with KS was characterized by a steep temporal gradient in which facts pertaining to the distant past were more accurately retrieved than facts concerning events that occurred just prior to the onset of their illness. Taken in conjunction with other recent studies of retrograde amnesia, these results suggest that neurologic patients exhibit at least three different patterns of remote memory loss.