In agreement with the neuropsychological findings, available anatomical data from patients with diencephalic or bitemporal amnesia suggest that these amnesias need not result from damage to a single functional system. In the case of diencephalic amnesia, the mammillary bodies and the dorsomedial thalamic nucleus have been implicated, but it is not yet clear which structure deserves the greater emphasis. In the case of bitemporal amnesia, the evidence suggests that the hippocampal formation plays a crucial role in memory functions; the possibility also needs to be considered that the hippocampal formation and amygdala may function conjointly in this regard. An alternative possibility that temporal stem damage is responsible for amnesia now seems quite unlikely.